a '<' or a '>'

a '±'

a '='

a '|'

a '&'

a '#'

a '<='

a '>='

a '<'

a '>'

a '*'

a field or a file

a file

a file

a field or a variable

a field

a variable

an expression

a picture

a pointer



a boolean expression

a date expression

a text expression

a numeric expression