This function is used to test if a custom field is defined by specifying a name. Note that the raw custom name, (Custom #), can also be entered. These raw custom names are only relevant if you are looking at the returned contents of a rename template.
The supplied name may contain any of the escape sequences described in Escape Sequences.
The function is only executed once per set of files while executing stepwise.
The action test state is set to true if the custom field is defined, otherwise it is set to false.
A Custom Field is Yes/No named variable is set as follows: If the custom field is marked as being a Yes/No value, the named variable will have a value of 1 otherwise it will be empty.
If the supplied name was a raw custom name, the display name will be returned in a Custom Field Display Name named variable.