Chapter 4 Reserved names in FTL
The following names cannot be used for top-level variables without square-bracket syntax (as .vars["in"]), since they are keywords in FTL:
- true: boolean value ``true''
 - false: boolean value ``false''
 - gt: comparison operator ``greater than''
 - gte: comparison operator ``greater than or equivalent''
 - lt: comparison operator ``less than''
 - lte: comparison operator ``less than or equivalent''
 - as: used by a few directives
 - in: used by a few directives
 - using: used by a few directives