# Identifiers

Identifiers are used as names of variables and functions. The length of the identifier can not exceed 63 characters.

Characters allowed to be written in an identifier: figures 0-9, the Latin uppercase and lowercase letters a-z and A-Z, recognized as different characters, the underscore character (_).The first character can not be a digit.

The identifier must not coincide with [reserved](/en/docs/basis/syntax/reserved) word.

Examples:

```
NAME1 namel Total_5 Paper

```

See also

[Variables](/en/docs/basis/variables), [Functions](/en/docs/basis/function)