Words that are specified for use in XQuery functions (for, if, etc.) are called keywords. Keywords in XQuery are specified in all lower case. XQuery distinguishes between upper-case and lower-case letters.

The following characters or elements can serve as separators in XQuery:

• Space (X'20')
• TAB (X'09')
• NL (X'0a')
• CR (X'0d')
• XQuery comment

(a) Where separators must be inserted

Separators must be inserted in the following places:

• Between two keywords
• Between a keyword and a qualified name
• Between a keyword and a numeric literal
• After a qualified name and before the subtraction operator (-)

(b) Where separators cannot be inserted

Separators cannot be inserted in the following places:

• Inside a keyword
• Inside a qualified name
• Inside a numeric literal
• Inside a character string literal
• Inside an operator
• Inside an XQuery path expression specified within //
• Inside an XQuery path expression specified within ..
• Inside an XQuery path expression specified within ::
• In an XQuery variable reference between the $ and the XQuery variable name
• In an XQuery comment between ( and :
• In an XQuery comment between : and )
• Inside a FLWOR expression specified within :=

(c) Where separators may be inserted

Separators may be inserted in the following places:

• In places not prohibited under Where separators cannot be inserted above, as well as before and after the following special characters:
  , . - + * ' " ( ) < > = ! / : ; | [ ] space (X'20'), TAB (X'09'), NL (X'0a'), and CR (X'0d')