Identifiers¶

Felix has a rich lexicology for identifiers.

C like identifiers¶

C like identifiers start with a letter, and are optionally followed by a sequence of letters, underscores, single quotes, hyphens, or ASCII digits.

The first character may also be an underscore but that is reserved for the system.

A letter may be any Unicode code point accepted by ISO C++ Standard as a letter, it must be encoded as UTF-8.

Hello
X123
a'
julie-marx
xИΫຜشஇᄗデՖ


Note again please, only ASCII digits are permitted.

Tex Identifiers¶

A leading slosh followed by a nonempty sequence of ASCII letters is recognised as an identifer. With suitable output machinery, the corresponding LaTeX or AmSTeX symbol should display if there is one.

\alpha


displays as

$$\alpha$$


No space is required after a TeX identifier. Therefore

\alpha2


encodes the symbol alpha followed by the integer 2.