Better words for "open-ended" and "multiple choice"?

I'm writing documentation for some code at work and I am trying to describe some parameters that must be specified by the user. Some of the parameters are specified with one word from a list of possible choices (e.g., "true" or "false"; "ags" or "wms"; "json", "xml", or "text"). Others are more "open-ended" and the user specifies anything they'd like (parameters like this include name, identifier, URL, etc).

I'd like to describe each of these two types of parameters. Are there words that describe one as open-ended and one as multiple choice? These descriptions I'm using don't seem to do it justice. They also seem to imply there is some kind of question involved when there isn't.

Does anyone have any ideas of what words I could use in my documentation to describe these two types of parameters?

Answer

For the "multiple-choice", you could use "enumerated"; however, it probably makes more sense to just list the options, using a full phrase: "either true or false", "one of: json, xml, text", etc.

For the "open-ended", you could use "free-form" or "arbitrary text"; but it's likely that there are some restrictions, in which case you can probably just describe those (e.g., "up to 128 characters", "cannot include whitespace") and leave it implied that there's not a fixed list of options.