There are several requirements for altering templates to customize function strings.
Function-string input and output templates are limited to 64K bytes. The result of substituting runtime values for embedded variables in function-string input or output templates must not exceed 64K.
Function-string input and output templates are delimited with single quotation marks (').
Function-string variables are enclosed within a pair of question marks (?).
A variable name and its modifier are separated with an exclamation point (!).
Language output templates involve additional related requirements.