If Genres are types, classes, or kinds of literature, art, music, etc., what to call the marks, signs, or formulas that identify a genre?

The literary-critical term is "conventions," which everyday speech might describe as

elements

standard features

expectations

standards

formulas

device

set-pieces

motifs

Metaphorically, conventions might be considered the genes or DNA of a genre—the building blocks or pieces that assemble a whole text. For instance, the conventions of a crime, a locked room, a mysterious note, an attractive but elusive woman, and a detective (professional or amateur) might be considered the conventions of the mystery genre.

Not rules but expectations (which can be purposefully frustrated)

Oxford English Dictionary
Convention: 9a. General agreement or consent, deliberate or implicit, as constituting the origin and foundation of any custom, institution, opinion, etc., or as embodied in any accepted usage, standard of behaviour, method of artistic treatment, or the like.

9b. In a bad sense: Accepted usage become artificial and formal, and felt to be repressive of the natural in conduct or art; conventionalism.

10a. A rule or practice based upon general consent, or accepted and upheld by society at large; an arbitrary rule or practice recognised as valid in any particular art or study; a conventionalism.

Definitions of convention on the Web:

• a large formal assembly; "political convention"
• something regarded as a normative example; "the convention of not naming the main character"; "violence is the rule not the exception"; "his formula for impressing visitors"
• (diplomacy) an international agreement
• conventionality: orthodoxy as a consequence of being conventional
• the act of convening
  wordnetweb.princeton.edu/perl/webwn 
• A convention is a set of agreed, stipulated or generally accepted standards, norms, social norms or criteria, often taking the form of a custom.
  en.wikipedia.org/wiki/Convention_(norm) 

 

• that lowest common denominator of truth and right to which society as a whole adheres, and which is the point of departure for (and is often scorned by), those with creative aspirations. antonym: creativity.
  ninthstreetcenter.org/Glossary.htm 

   

• Any widely accepted literary device, style, or form.
  www.gale.cengage.com/free_resources/glossary/glossary_bc.htm 

   

• A device of style or subject matter so often used that it becomes a recognized means of expression. For example, a lover observing the literary love conventions cannot eat or sleep and grows pale and lean. ...
  www.cliffsnotes.com/WileyCDA/Section/Literary-Terms-Poetry-Glossary.id-305499,articleId-30165.html 

 

Not rules but expectations (which can be purposefully frustrated)

One way we practice judgment is to measure our reactions to changes to our expectations.

Does a specimen or example fall short of expectations, or take us further?

If further, was that a good change or a bad change?

Knowledge of genres = yardsticks, standards of measurement

Standards do not equal rules. Standards can be bent, raised, lowered, varied to need.

 

adjective form: "conventional"

Definitions of conventional on the Web:

• following accepted customs and proprieties; "conventional wisdom"; "she had strayed from the path of conventional behavior"; "conventional forms ...
• conforming with accepted standards; "a conventional view of the world"
• (weapons) using energy for propulsion or destruction that is not nuclear energy; "conventional warfare"; "conventional weapons"
• represented in simplified or symbolic form
• ceremonious: rigidly formal or bound by convention; "their ceremonious greetings did not seem heartfelt"
  wordnetweb.princeton.edu/perl/webwn 
• A convention is a set of agreed, stipulated or generally accepted standards, norms, social norms or criteria, often taking the form of a custom.
  en.wikipedia.org/wiki/Conventional 
• ordinary, commonplace
  en.wiktionary.org/wiki/conventional 
• conventionally - ordinarily, by convention
  en.wiktionary.org/wiki/conventionally 
• Something which grows out of or depends upon custom, or is sanctioned by general usage.
  chestofbooks.com/home-improvement/woodworking/Carpentry-For-Boys/Carpentry-Glossary-Part-2.html