# Identifiers

An identifier is any nonempty Unicode1 string of the following form:

Either

• The first character has property XID_start
• The remaining characters have property XID_continue

Or

• The first character is _
• The identifier is more than one character, _ alone is not an identifier
• The remaining characters have property XID_continue

that does not occur in the set of keywords.

Note: XID_start and XID_continue as character properties cover the character ranges used to form the more familiar C and Java language-family identifiers.

1

Non-ASCII characters in identifiers are currently feature gated. This is expected to improve soon.