An identifier is a sequence of one or more non-delimiter characters. Identifiers are used in several ways in Scheme programs:
Scheme accepts most of the identifiers that other programming languages allow. MIT/GNU Scheme allows all of the identifiers that standard Scheme does, plus many more.
MIT/GNU Scheme defines a potential identifier to be a sequence of non-delimiter characters that does not begin with either of the characters `#' or `,'. Any such sequence of characters that is not a syntactically valid number (see Numbers) is considered to be a valid identifier. Note that, although it is legal for `#' and `,' to appear in an identifier (other than in the first character position), it is poor programming practice.
Here are some examples of identifiers:
lambda q list->vector soup + V17a <=? a34kTMNs the-word-recursion-has-many-meanings