I recently saw this video demonstrating where "A113" has been inserted into Pixar movies by the animators or script writers. The implication being that "A113" is a code for Adrenochrome. The official story is that:

A113 is a studio code and its variants are an inside joke and Easter egg in media developed by alumni of California Institute of the Arts, referring to the classroom used by graphic design and character animation students. https://en.wikipedia.org/wiki/A113

The California Institute of the Arts, or CalArts, said in a statement emailed to Reuters that room A113 is a former Character Animation classroom where many animation artists, including Pixar staff Brad Bird, Andrew Stanton and Pete Doctor studied while enrolled at CalArts. https://www.reuters.com/article/idUSL1N3941LO/

The Reuters "fact check" is technically accurate because I was trying to make the same connection and failed. There is nothing inherent about Adrenochrome or its properties where "113" appears.

But it was obvious to me that some connection was there...

• Googling "A113 chemical" reliably returns the Adrenochrome wikipedia page as the first result
• The door of the room is deliberately painted "blue pill"
• this kind of repeating symbolism is unlikely to be merely a "former classroom" easter egg especially given the history of symbols found in children's programming

Then I realized what their code was:

Have you ever seen the abreviations "i18n" and "l10n"? They are examples of shorthands used in computing for "Internationalization" and "Localization". Just replace the middle of the word with the count of letters removed.

"Adrenochrome" has 12 letters. Instead of "A10e", they counted to the last letter: "A11".

But about the 3 at the end? They added the first character from its standardized chemical name:

Adrenochrome 3-Hydroxy-1-methyl-2,3-dihydro-1H-indole-5,6-dione

A113.