= TeX character code
{c}
A \b[TeX character code] is the numerical component identifying a character in <TeX>'s character model. An ordinary character <TeX token> combines that code with a <TeX category code>. Classic <TeX> uses an eight-bit character-code range, 0–255.<TeX source code by Donald E. Knuth>[Character set: ASCII_code; token representation and cur_chr]{ref}
For example, under the usual <ASCII> mapping, `a` has code 97. Reading it once with category 11 and again with category 12 produces the pairs $(97,11)$ and $(97,12)$. The first component stays the same; the syntactic classification changes. This is why a <TeX macro> can distinguish inputs that look alike on the page.
The number does not identify a universal <glyph>. A <computer font> supplies the printed form, and a <glyph index> belongs to that font. The classic range should also not be treated as a restriction on every extended <TeX> engine.
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