Reverse architecting conventional footwear. Towards an A3 Architecture Overview that supports development of alternative footwear architectures.

The architecture of contemporary footwear is the result of a long history of footwear development. In this history, part of the argumentation behind the architecture has been lost, causing footwear developers to make decisions based on habits and badly underpinned assumptions. New insights on the negative influence of most conventional footwear on human (foot) health and the design freedom that arises from modern manufacturing techniques, create the urge to reconsider the common way of developing. By reverse architecting conventional footwear, this paper derives an A3 Architecture Overview of conventional footwear. In the future this overview should provide a tool for enabling product evolution towards healthy footwear, by allowing developers to consciously and purposefully deviate from ‘the standard architecture’ while taking into account the consequences of design decisions they make. The approach that is described in this paper is also applicable to the development of architecture overviews for other product families.


Background
In the Western world, footwear is so commonly used that it has become inherently part of our being in the world. It is via footwear that users are in almost constant contact with different types of environments. While serving as an extension of the human body, the earliest footwear seems to merely have had a protective function (Stewart 1972;Swallow 1987). Nowadays, footwear developers have succeeded to include many more functionalities. These functionalities, however, often partly -or even entirely -show a mismatch with the functions of the human body. Footwear developers mistakenly see the foot as an inflexible lever which is fragile and thus needs to be supported and packaged (Robbins & Hanna 1987). Instead of preserving healthy feet, this can have many adverse shortand long-term effects; the natural shape of the foot can be deformed, loading in the joints can be changed, plantar sensation can be reduced, the foot-strike pattern can be altered, the foot-strength and elastic energy storage can be reduced, evaporation of perspiration can be reduced and the maturation of the foot can be hampered, ultimately resulting in pain, reduced mobility and high societal costs (Buldt & Menz 2018;D'Août et al. 2009;Frey 2000;Lieberman et al. 2010;Perl, Daoud & Lieberman 2012;Rose et al. 2011).
Considering those insights, together with the newly obtained design freedom that results from the emergence of modern manufacturing techniques, the common way of developing footwear might unintentionally inhibit footwear developers to use the full potential of knowledge and technology at hand. To support design efforts towards creating product evolutions, first the architecture of present footwear has to be documented. Reverse architecting using the so-called A3 Architecture Overview (A3AO) -containing a physical view (showing design decisions), a functional view (providing design argumentation) and a quantification view (providing key-drivers) -can be employed for that purpose (Borches 2010). The aim of this paper is, therefore, to derive an A3AO for footwear development by reverse architecting conventional footwear. In the future, this A3AO should provide a tool for enabling product evolution towards healthy footwear by allowing footwear developers to consciously and purposefully deviate from 'the standard architecture', while constantly allowing them to consider the consequences of the design decisions they make.

Methods
In reverse architecting, usually three different process phases, being Information Extraction, Abstraction, and Presentation are executed in an iterative manner (Müller, Wong & Tilley 1995). In reverse architecting conventional footwear, also these three phases are executed. The information extraction phase is executed by analyzing descriptions -that are used by academics as well as in industry -in relation to the parts of non-athletic (men's and women's) footwear as well as athletic footwear. The phase results in an overview of the components of different types of footwear as well as the functions thereof. By comparing the components and functions and by boiling down to the basic elements during the abstraction phase, both a physical description and a functional description is made that is common for most conventional types of footwear. Together with a shortlist of the key-drivers (Bonnema 2008;Heemels et al. 2006) that represent the high-level requirements of specific footwear (quantification view), these provide the views to be presented in an A3 Architecture overview for conventional footwear (presentation phase).
The physical and functional descriptions are evaluated by analyzing a number of random pictures showing footwear anatomy and by iteratively comparing the represented parts / terms with the results until then. The parts and functions that are still lacking can subsequently be included in the final physical and functional view on the A3 Architecture Overview (see Figure 1).

Physical View
To create a better understanding of the architecture(s) of conventional footwear, first an overview (table) has been made of the terminology related to the functional parts of conventional footwear (Appendix A). The appendix is organized per sub-assembly of the shoe (shaded rows). The parts of each assembly are organized in individual rows; sub-parts are indented. As conventional footwear comes in many different appearances, dependent on the purposes it is used for, the overview makes a distinction between non-athletic footwear (source columns 1 and 3) and athletic footwear (source columns 2 and 4); those types of footwear show a relatively large difference in the materials, components and manufacturing techniques that are used . Where athletic footwear is largely the same for both men and women, non-athletic footwear shows some differences in this respect. These differences, however, mainly concern the geometry of parts that are used. Therefore, the overview does not have to make a specific distinction in this respect.
The sources that have been used to create the overview were selected to vary both in academic (source columns 1 and 2) and industrial (source columns 3 and 4) nature. This was done to investigate whether there is any difference in the use of terminology between the two. The distinction is also visible in the columns of the table. An initial number of resources was selected to start with (  that represent the academic viewpoint, and (C&E_Fashions 2019; Motawi 2015) that represent the industry viewpoint). From the sources, quotations were collected in which terminology related to the functional parts of footwear was used. This terminology was underlined, and the citations were structured based on these terms (rows in table Appendix A). When different terms were considered to address a similar part, these terms are presented in the same row. It is important to note that this does not imply that the terms are full synonyms. In the attempt to complement the overview, a number of additional resources ( Eventually, a number of fields in the table (in appendix A) remained empty. These empty fields can be explained by the different architectures of non-athletic and athletic footwear as well as the lacking need for academics to address the terminology related to specific (sub)parts of an assembly.
The terminology was eventually used to create the physical description of conventional (non-athletic and athletic) footwear presented in Figure 2. When multiple terms were mentioned in the same row of the table, a general term was selected to be used for the physical description. An additional description of a non-athletic women's pump was added to show the large overlap in terminology with non-athletic men's footwear while having a complete different appearance; the represented shoe style ('pump') merely consists of fewer parts and has only one term (platform) that is specific for this type of shoe. It should be noted that Figure 2 gives a simplified representation of all parts (and corresponding terminology); for a full overview of all terminology, Appendix A should be referred to.
In each quotation presented in the overview in Appendix A, a possible description of the function of the part at hand was made italic. The italic descriptions of functions were used to derive the functions of conventional footwear in the next section.

Functional View
To derive the functions that are general for most types of conventional footwear, the terminology from the physical view was used and the italic function descriptions (see Appendix A) were listed together with these terms. In making Table 1, the function descriptions were rephrased by using terms from the 'Functional basis reconciled function set' defined by the National Institute of Standards and Technology, NIST (Hirtz et al. 2002). This was done with the aim to boil down to a limited and uncluttered set of different functions per part, that adheres to accepted terminology.    Table 1 and by removing the duplicates (see Table 2).

Quantification View
To define the quantification view, again the three reverse architecting phases were executed (Müller, Wong & Tilley 1995). As the quantification view was not really focused on in this phase of the research, this was done in a quick manner. First, information was extracted by reviewing literature on shoe selection criteria (Enke, Laskowski & Thomsen 2009;Goonetilleke & Luximon 2001;Miller 1976). The following shoe-selection criteria were mentioned: Arch type, Shoe design, Color, Appearance, Cost, Brand, Comfort, Fit (Enke, Laskowski & Thomsen 2009); Fashion, Price, Comfort, Fit, Performance, Durability (Miller 1976); Size, Shape, Flexibility, Style, Weight, Inside shoe climate, Materials, Tread, Cushioning (Goonetilleke & Luximon 2001). It is interesting that 'healthfulness' is not mentioned by these sources as a selection criteria. Recent insights into the negative influence of most conventional footwear on human (foot) health (Buldt & Menz 2018;D'Août et al. 2009;Frey 2000;Lieberman et al. 2010;Perl, Daoud & Lieberman 2012;Rose et al. 2011), however, might cause healthfulness to become a key-driver. Therefore, this term was also included in the overall list.
Abstraction and merging of the criteria eventually lead to the following shortlist of key-drivers that, for now, establish the quantification view: • Price • Comfort • Appearance • Durability • Performance

• Healthfulness
Together, these key-drivers represent the interests of the end user. We need to expand and update the set to also include interests of other stakeholders, like the producer and store operator.

Evaluation
To evaluate both the physical and functional overviews that were established, first a number of pictures of footwear anatomy was randomly collected via Pinterest (see Figure 3) and the used terminology was compared with the overviews in Appendix A and Figure 3.
The comparison lead to the following list of parts that were not yet described: • Toe burst panel; A part that is used to reduce wear to the upper caused by the toes/nails. The function of the toe burst panel can also be fulfilled by the toe-box/toe cap or mudguard.
• Mustache; A part with a mustache shaped pattern, added on the outside of the quarter, at the back, above the counter. The function of the mustache is similar to that of the counter and is used in classic sneakers.
• Lace-tip: The strengthened tip(s) of the laces. The tips allowing for easy pushing/pulling the laces through the eyelets.
• Bumper: The rubber strip attached to the forward facing part of a sneaker sole. The function is to decrease wear to the front of the sole.
• Foxing: The term foxing is used for almost any additional piece of leather/fabric attached to the outside of the vamp/quarter to add additional strength or to reduce wear, similar to an 'overlay'.
• Back-strap/rear-strap: The loop that is attached to the back of the quarter, sometimes as an extension of the back-stay. It can be used for easy shoe-access and prevents the back of the quarter from being suppressed.
• Back-tab: A different word for Achilles tendon protector.
• Air (or gel) Unit: An air (or gel) chamber added to the midsole for additional suspension.
• Insertor support / support insert: An insert in the midsole for additional support / to constrain motion.
• Rearfoot stabilizer: a support insert in the heel part of the midsole, to stabilize the rearfoot.

Conclusions
The established A3 Architecture overview shows the result of the decomposition of conventional footwear in relevant architectural aspects. These aspects form a solid basis to enable future footwear development and support the well thought-through development of new architectures. The overviews provide stakeholders of footwear development with means to easily discuss alternative requirements and/or key-parameters, alternative trade-offs, and to enable them to anticipate the impact thereof. In particular the so far undervalued healthiness of footwear can be improved using this architecture description, without compromising existing requirements.

Future work
The A3AO of Conventional Footwear can only prove its success when it is being used by footwear developers and has the desired results. As the A3AO is developed in the context of a bigger project on tools and guidelines for the development of healthy footwear, this will be the first area of application. In relation to this project, it will be complemented with technical knowledge on e.g. materials and production techniques and in-depth understanding of different stakeholder needs (shoe users, producers, shops, etc.). The use, however, is not limited to this project. It is well imaginable that it can also form a good basis for evolutionary developments in e.g. safety shoes. Moreover, the approach that was used in this paper can be applied to develop architecture overviews for other product families as well. -"The components of a shoe can be grouped broadly into those parts that make up the upper and those parts that constitute the lower or bottom."  -"Materials that can be used for shoe uppers can also be used in shoe soles…"  -"One of the most common methods currently used for attaching the upper to the lower is termed "Strobel" lasting."  -"There are four basic components of the athletic shoe: outsole, midsole, insole, and the upper."  "…to bond the upper parts and soles…" or " in which the upper and sole of the shoe are stitched together" or "The upper part of the shoe, not including the sole" (C&E_Fashions 2019) Outsole or sole unit: "The bottom component of a shoe that provides grip and traction. The outsole is commonly rubber, but can be high density PU or EVA foam. Dress shoes may have leather bottoms."  outsole/ outersole / bumper -"The outsole is the protective layer of material between the plantar surface of the foot and the ground."  "The outsole is the portion of the shoe that contacts the ground. It provides traction and protects against frictional forces."  "The outsole is the layer of the shoe that comes in contact with the ground." and "The outsole not only helps in maintaining traction but also provides durability, shock absorption, torsional rigidity, and flexibility."  "…a thin rubber outersole"  -"Outsole: The very bottom of the shoe that contacts the ground"(C&E_Fashions 2019) -"This is the outer most sole of the shoe, which is directly exposed to abrasion and wear." And "Ideal soling materials must be waterproof, durable and possess a coefficient of friction high enough to prevent slipping." ) -Bumper: The rubber strip attached to the forward facing part of a sneaker sole. The function is to decrease wear to the front of the sole.

Biography
Outsole or sole unit: "The bottom component of a shoe that provides grip and traction. The outsole is commonly rubber, but can be high density PU or EVA foam. Dress shoes may have leather bottoms."  "Since it's the initial point of impact, the outsole often includes features like decoupled heels and footbridges that assist in the overall cushioning and support" (Runner'sWorld 2009) tread (waffles/ lugs/nubs/r ipples) -"Nubs, ripples, and waffles are commonly placed on the outsoles of running shoes. The original reason for this type of outsole design was to improve traction during cross-country running. It has been shown that the waffle or nubbed outsole will contribute to shock attenuation while running on asphalt and concrete."  "Tread is the part of the outsole that comes in direct contact with the ground. On road-running shoes, treads supply cushioning while giving the shoe a bit of added traction. Runners often refer to these small raised treads as waffles, in reference to the first popular Nike outsole created by Bill Bowerman with the help of his wife's waffle iron. On trail shoes, where traction is more important than cushioning, the raised treads are called lugs."(Runner'sWorld 2009) -"The outsole lug is a small block of rubber that makes the tread grip"  midsole -"The midsole of the shoe is an added layer of material located in-between the outsole and insole of a shoe"(Blazer, Jamrog & Schnack 2018)" -"Thick cushioned midsoles are commonly added to footwear to provide cushioning and protection from the environment." (Davis 2014) -"The midsole is an important part of the bottom of the shoe. It helps in providing cushioning and stability to the feet. The more cushioned the midsole, the less stability it provides to the feet; therefore, a balance between cushioning and stability to the feet is vital in a shoe" "A reinforced platform under the arch between the heel and the sole that prevents the shoe from bending in the middle. The footbridge, or shank, supports the foot between the heel of the shoe and the forefoot and supplies torsional rigidity to prevent the shoe from twisting easily under landing pressure (excessive twisting can lead to runner's knee and other joint alignment injuries)." (Runner'sWorld 2009) "Since it's the initial point of impact, the outsole often includes features like decoupled heels and footbridges that assist in the overall cushioning and support" (Runner'sWorld 2009) -Insertor support / support insert: An insert in the midsole for additional support / to constrain motion. Heel/ rearfoot stabilizer -"The heel is a component in numerous types of shoes and can be of various lengths depending on the specific style." And "Men's heels are standardized in shape for most shoe styles and have a heel height of about 1 inch. Women's heels come in numerous shapes and styles to complement different fashions of dress."  -"Heel -"Heel" can refer to both the rear, padded area of the underside of the foot, as well as the solid part of a shoe that supports the heel cup."(C&E_Fashions 2019) -"The heel is the part of the sole that raises the rear of the shoe in relation to the front."(ShoeGuide 2019) -"When the heel section sits lower than the forefoot the style is called a 'negative heel'"  -Rearfoot stabilizer: a support insert in the heel part of the midsole, to stabilize the rearfoot. "In 85mm heel design, some designers will add a wedge or front platform to increase the height. However, the height of the insole should be kept to 85mm. In drawing shoes with a front platform, the heel must be extended and elongated to the same height as the front platform."  Source Terminology Academic & Non-Athletic Academic & Athletic Industry & Non-Athletic Industry & Athletic upper /body -"The components of a shoe can be grouped broadly into those parts that make up the upper and those parts that constitute the lower or bottom." and "The sections of the upper include the vamp, quarter, toe box, throat, insole board, and topline."  -"The components include: -Body -Heel -Insole -Sole -Platform."  -"The upper of a shoe is the region covering the dorsum (top) of the foot"  -"The upper is the part of a shoe that covers the top and sides of the foot. The construction uses a highly breathable fabric that can prevent heat buildup, at the same time enhancing durability and providing water resistance, hence making it washable. The typical material used is nylon. Reinforcements are added as leather or synthetic leatherlike materials."  -"The upper part of the shoe, not including the sole. May be made from leather, fabric or synthetics."(C&E_Fashions 2019) -"The entire part of the shoe that covers the foot."(ShoeGuide 2019) -"In the most basic terms, the upper is the top part of a shoe that encases the foot. It's made from a soft, breathable mesh that gets stretched around a foot formor last -to mould it into shape. This mesh is reinforced with more durable material and moulded plastic that holds the foot in place"(Runner'sWorld 2009) -"The part of a shoe that encases your foot and essentially holds it in place is called the upper. It covers the entire top part of the shoe." And "The type of material used is generally leather or synthetic leather, which will allow your feet to breathe. These materials will also protect your feet."(BootMoodFoot 2019) vamp -"The vamp is an essential part of the nonathletic and athletic shoe that covers the forefoot and toes. In nonathletic shoes, the vamp can consist of one or several pattern pieces, depending on the toe design intended for the shoe."  -"In athletic footwear, the vamp is usually made from one piece of material to reduce the number of seams that could cause irritation to the dorsum of the toes." ( -"If a shoe is to retain its shape, it is necessary to stiffen it at the toe and heel; this leads to the addition of heel and toe stiffeners, or counters."  -"The toe box is the roof covering the toes inside the shoe, which acts to maintain the shape of the anterior shoe and allows adequate room for toes." (Blazer, Jamrog & Schnack 2018) -"The toe box refers to the roofed area over and around the part of the shoe that covers the toes (Fig. 4). The function of the toe box is to retain the shape of the forefoot and allow room for the toes. The height and width of the toe box is dictated by the shape of the last used to construct the shoe.  laces/ (lacing systems)/ lace-tip (can be replaced by velcro / zippers) -"To achieve total foot stabilization, a high lacing pattern utilizing at least six eyelets is necessary to accomplish midfoot stabilization in addition to a firm heel counter with a rearfoot stabilizer (McPoil, 1997)." (McPoil 2000) -"They're the strings used to close the eyelets and hold the shoe on your foot"(BootMoodFoot 2019) -"Lacing systems in sneakers let you customize how the shoe fits you. The arrangement and location, as well as the number of eyelets, allow you to decide how much adjustment you want."(BootMoodFoot 2019) …"Sometimes you will be able to lace them right up to the heel collar, especially with high-top style sneakers."(BootMoodFoot 2019) -Lace-tip: The strengthened tip(s) of the laces. The tips allowing for easy pushing/pulling the laces through the eyelets.
quarter/ quarter panel / (shaft/top) -"The back half of the nonathletic shoe upper is termed the quarter. In better-grade shoes, the quarter consists of an inside and outside section or panel attached to the vamp in the front and joined together in the rear of the shoe at the back seam. The anterior superior part of the quarter contains the eyelets for the laces."  -"In an athletic shoe, the vamp and quarter panels are often one continuous piece of nylon or leather with additional leather pieces added to reinforce critical areas of the shoe."  -"The rear and sides of the upper that covers the heel that are behind the vamp. The heel section of the quarter is often strengthened with a stiffener, which helps support the rear of the foot. Some shoe designs use a continuous piece of leather for the vamp and quarter."(ShoeGuide 2019) -"In boots the quarter is referred to as 'top'" ) -"This term refers to the sides of the shoe which cover the area from the vamp to the heel. The quarter is usually reinforced with a stiffener at the heel area, to support the back of your foot"(BootMoodFoot 2019) -"The shaft of the boot which is the part of a boot that covers your ankles, calf, and leg. They can vary in length and be secured with laces, zips, or just pull on."(BootMoodFoot 2019) -"In boots the quarter is referred to as 'top'"  "The shoe part Quarter Panel: The Quarter Panel is the main shoe pattern part on the side of the shoe pattern. The Nike Swoosh, New Balence N and the Vans V-Bar are all located on the quarter panel"  overlay /saddle /arch bandage / foxing -"Reinforcement added to the region of the medial longitudinal arch is termed the saddle if it is added to the outside of the shoe or the arch bandage if it is added to the inside of the shoe"  -Foxing: The term foxing is used for almost any additional piece of leather/fabric attached to the outside of the vamp/quarter to add additional strength or to reduce wear, similar to an 'overlay'.
-Overlay: "These strips work with the laces and eyestays to make the shoe conform to the shape of the foot."(Runner'sWorld 2009) -Overlay: "Pretty much anything that is stitched or bonded to the upper, though the term most commonly refers to the reinforcing strips that provide structure to the shoe."(Runner'sWorld 2009) -Overlay: "An upper part which is over another part. The Nike Swoosh logo is what I would call and Overlay part."  -"Saddle: A reinforced mesh that tightly wraps the midfoot and supports the arch. If it's not snug, the foot will move inside the shoe, causing blisters."(Runner'sWorld 2009) (heel) stiffener/ (heel) counter/ backstay/ foxing / mustache If a shoe is to retain its shape, it is necessary to stiffen it at the toe and heel; this leads to the addition of heel and toe stiffeners, or counters."  -"The counter is a component of the quarter that stabilizes the hindfoot in the shoe and retains the shape of the posterior portion of the shoe."  -"The foxing is an additional piece of leather that covers the counter externally."  "The heel counter is the stiff posterior backing of the shoe that stabilizes heel motion, which helps support the shape of the posterior aspect with increasing wear, while keeping the foot striding in a forward direction."  -"Heel: This is the part at the back of the shoe which is usually stiffened. It may have a seam up the center of it, where the upper is stitched." And "Heel counter: The name given to the material used to reinforce and stiffen the heel. It can't be seen by the eye as it's enclosed between the outer and inner linings of the shoe."(BootMoodFoot 2019) -"A stiff piece of material at the heel of a shoe positioned between the lining and upper that helps maintain the shape of the shoe. The counter helps strengthen the rear of the shoe."(ShoeGuide 2019) "The counter or backstay is a strip of leather that runs up the back of a shoe or boot. This piece of leather used for additional stability and sometimes to connect the two halves of the quarter."  "Backstay: This is another part that can't be seen, and it helps reinforce the counter running down the back of the heel."(BootMoodFoot 2019) "In some children's shoes and athletic footwear the stiffener is extended on the medial of the arch to provide an anti-pronatory wedge." ) "Internal or external, the heel counter is the pattern part that covers the heel of the shoe. The internal heel counter can be made of rubber (for vulcaized shoes), thermo plastic (for cold cement shoes), chemi sheet (for really cheap shoes), or leather for dress shoes. Depending on the shoe type the counter can be thin and soft or stiff and sturdy."  -Mustache; A part with a mustache shaped pattern, added on the outside of the quarter, at the back, above the counter. The function of the mustache is similar to that of the counter and is used in classic sneakers. The topline refers to the top rim of the quarter in a nonathletic shoe." And "When the foot is placed in the shoe, the topline should fit snugly against the heel.  "In athletic footwear, the topline is usually padded and is termed the collar."  -"The collar covers the ankle and has a projection that comes up above the heel to help protect the Achilles tendon from friction and irritation"  -"topline: The top edge of the upper"(ShoeGuide 2019) "The top edge of the sides and back of the quarter describes the topline." ) -"Made out of a soft material, the collar should wrap just below the ankle and supply a snug, gap-free fit." (Runner'sWorld 2009) -"Heel collar: This is the name given to the cushioned area around the top of the heel opening on a sneaker. Also known as the heel cuff, it is generally padded for added comfort and thicker than the rest of the upper. There is often a loop attached to it as well, which helps you pull your sneaker onto your foot"(BootMoodFoot 2019) -"heel notch: A relief cut that allows the runner to flex and bends without the shoe rubbing on the Achilles tendon. Also called Achilles tendon protector or Achilles tendon notch." ) -Back-strap/rear-strap: The loop that is attached to the back of the quarter, sometimes as an extension of the back-stay. It can be used for easy shoe-access and prevents the back of the quarter from being suppressed. eyelets /hooked eyelets/ speed hooks/ webbings/ (grommet) -"To provide stability, footwear should have a firm counter, a shankpiece or wedge, and four to six pairs of eyelets" and "The anterior superior part of the quarter contains the eyelets for the laces."  -"To achieve total foot stabilization, a high lacing pattern utilizing at least six eyelets is necessary to accomplish midfoot stabilization in addition to a firm heel counter with a rearfoot stabilizer (McPoil, 1997)."  -"Eyelets are the holes that are punched in the upper to allow the foot to be laced up. Eyelets are usually reinforced with a metal grommet to protect the structural integrity of the upper and to avoid fraying."  -eyelets: "These are the holes for the laces to be threaded through."(BootMoodFoot 2019) -"Speed hooks are little metal doo-hickeys that make tying your shoes so much easier. Instead of having to lace up your boot all the way to the top, you can hitch your laces over these hooks. These are also referred to as hooked eyelets."  -"In Oxford style lacing shoes, the eyelet section is formed by the superior part of the quarter (while the underlying tongue is part of the vamp). In the Gibson style the lacing segment forms part of the vamp"  -"A hole through which you lace up a shoe"  -"can feature webbings, eyelets, etc."  Lining(s)/ the sock "Hydrophilic leather that is ideal for soles, linings and insoles, is less malleable, harder and more difficult to work with than either synthetic-or chrome-tanned leathers."  -"Most shoes include a lining on the inside of the shoe, around the vamp and quarter. These linings improve comfort, and can help increase the lifespan of the shoe."(ShoeGuide 2019) "In quality shoes the quarters and vamps are lined to enhance comfort and durability. Linings may consist of various materials i.e. leathers, fabrics, and manmade synthetics. The lining on the insole segment is called 'the sock' and may be full-length, three-quarter or just the heel section. Many linings are made of synthetic material and are usually confined to the quarters and the insock."  -"Linings of a shoe 1. Quarter Lining: horseshoe shape around back part of shoe 2. Vamp Lining: inside upper of forepart and toe of shoe 3. Sock Lining: covering all OR part of the top surface of the insole."  welt/ feather -Welt: "A strip of material that joins the upper to the sole."(ShoeGuide 2019) -"The welt is a strip of leather around the edge of the sole and to which the upper is attached. There are a number of different styles of welts, the most complicated of which are becoming more and more expensive to make. But a high quality welt can make all the difference in the world. A Goodyear welt for example should make your shoe or boot water resistant and allow for the outsole to be replaced should it wear out."  "The strip of material which joins the upper to the sole. Most shoes will be bonded by Goodyear-welted construction. Some shoes use an imitation welt stitched around the top flat edge of the sole for decorative purposes, but it is not a functional part of the shoe." ) "the welt is attached to the feather of the insole.

TOP-LEVEL VIEW
In the Western world, footwear is so commonly used that it has become inherently part of our being in the world. It is via footwear that users are in almost constant contact with different types of environments. While serving as an extension of the human body, the earliest footwear has had both a protec�ve and a symbolic func�on. Nowadays, footwear developers have succeeded to include many more func�ons, partly -or some�mes en�relytaking over func�ons from the human body (see func�onal view).
In its basis, conven�onal footwear consists of two major sub-assemblies: the so-called 'lower' and 'upper'. During manufacturing, the upper is moulded around a shoe last (a solid model of the foot) and a�ached to the lower; the two become inseparable.

INTRODUCTION
The architecture of nowadays conven�onal footwear is the result of a long history of footwear design, manufacturing and marke�ng. In this long history, part of the argumenta�on behind the architecture has been lost, causing footwear developers to make decisions based on beliefs, habits and badly underpinned assump�ons.
With new insights on the nega�ve influence of most conven�onal footwear on human (foot) health in combina�on with the design freedom created by modern manufacturing techniques, the common way of developing might hamper footwear developers in using the full poten�al of knowledge and technology at hand.
To allow footwear developers to consciously and inten�onally deviate from the conven�onal architecture and work towards product evolu�ons, this A3 architecture overview shows the basics of conven�onal footwear. By making footwear developers conscious about the design decisions they make in rela�on to 'the standard' (func�ons, key-parameters, physical appearance), they can purposefully decide to deviate from this while overlooking the consequences, independent of the type of evolu�on they strive for.

PHYSICAL VIEW
The terminology that is listed in Appendix A was eventually used to create the physical descrip�on of conven�onal (non-athle�c and athle�c) footwear presented the physical view. When mul�ple terms were men�oned in the same row of the table in Appendix A, a general term was selected to be used for the physical descrip�on. An addi�onal descrip�on of a non-athle�c women's pump was added to show the large overlap in terminology with non-athle�c men's footwear while having a complete different appearance; the represented shoe style ('pump') merely consists of less parts and has only one term (pla�orm) that is specific for this type of shoe.
It should be noted that the physical view (see PHYSICAL VIEW on the other side of this sheet) merely shows three different types of shoes; many more different types of shoes exist, with different appearances. The terminology of parts, however, largely remains the same for all these different types. For a more complete list of similar terms for parts, the use of Appendix A should be consulted.

FUNCTIONAL VIEW
The func�onal view on the other side of this sheet shows a list of the func�ons that can be fulfilled by conven�onal footwear. Informa�on for this func�onal view was collected by analyzing descrip�ons -that are used by academics as well as in industry -in rela�on to the parts of non-athle�c (men's and women's) footwear as well as athle�c footwear. The analysis resulted in an overview of the components of different types of footwear as well as the func�ons thereof (see Appendix A).
The overview was checked by comparing with a total number of 18 pictures of footwear anatomy from which the terminology was compared and based on which a few addi�ons were made. From the updated overview the func�on descrip�ons were rephrased by using terms from the 'Func�onal basis reconciled func�on set' defined by the Na�onal Ins�tute of Standards and Technology, NIST [1]. This was done with the aim to boil down to a limited and unclu�ered set of different func�ons per part, that adheres to accepted terminology (see Table 1 in [2]). Eventually a general list of possible footwear func�ons was derived by combining the func�ons from Table 1 in [2] and by removing the duplicates. The list is represented in the FUNCTIONAL VIEW on the other side of this sheet

KEY-PARAMETERS & REQUIREMENTS
Footwear users can have many different criteria for selec�ng a specific (type of) shoe. Review of literature on shoe selec�on criteria lead to a list of (some�mes overlapping) criteria that could eventually be summarised into a list of 6 main criteria. For designers, these criteria are the key-drivers that should be reckoned during design. A suitable balance should be found between: Together these criteria establish the quan�fica�on view.

CONVENTIONAL FOOTWEAR (SUMMARY)
KNOWN ISSUES * Footwear developers have -for a long �me -seen the foot as a fragile body part that needs to be protected, supported and packed. Today, more and more research illustrates the health benefits that are gained by allowing our feet to func�on in their most natural way. The key-parameter 'healthfulness' seems to become increasingly relevant, and as a result, some of the func�ons that are currently fulfilled by footwear might need to be carefully re-considered and some�mes even be re-allocated to the human body. * Due to technology advances and modern manufacturing techniques, new possibili�es come within range that can allow footwear developers to reconsider: -shoe customisa�on possibili�es, -the use of materials, -the use of solid and inflexible lasts, -the dis�nc�on between upper & lower, -etc.

ROADMAP
In future footwear development, three different scenarios can already be foreseen:

Short term
In a first scenario, footwear s�ll has a conven�onal product architecture and is being produced by using conven�onal manufacturing techniques and materials.
The key-drivers, however, might be quan�fied differently due to changing trends (e.g. in foot health), leading to changes in the func�ons of footwear.

Mid term
In a second scenario, footwear with a conven�onal product architecture can be produced by using modern and unconven�onal manufacturing techniques or materials, e.g. allowing for affordable (mass) customisa�on. Footwear users are able to customise their footwear based on price / comfort / appearance / durability / performance and healthfulness demands.

Long term
In a third and most futuris�c scenario the second scenario is supplemented with the possibility to create footwear that has a completely different product architecture.