Double Quotes in Constraint Expressions

DAP 3.2

Double quotes (") can be used to quote any identifier in a Constrain Expression.

Rationale

Many data sets us identifier names which contain characters other than those that qualify as an identifier in a programming language like C. For example, using an ampersand (&) in a variable name will cause a conflict with the meaning of an ampersand as a prefix AND operator in the CE's selection clause. Enclosing the identifier name in double quotes resolves the ambiguity. The same can be said for other DAP/CE meta-characters like the dot (.) which serves as a separator for the name of a Structure, et c., and its fields.

examples

scale factor

"scale_factor" or scale%20factor or "scale%20factor"

level_2 data.scale factor

"level_2 data"."scale Factor" and the %20 variants. Note that each component of the full field name is quoted separately so the dot (.) will be read by the parser

level.2.data&errors

"level.2"."data&errors" In this example, the first dot is part of the variable name and the second is a separator between a field and its container