Hello! Could anyone tell me what the character limit for the following data fields are?
File ID
Version ID
You can find the information for any particular field/value for the Dropbox API in the documentation. For example, it sounds like you're referring to the 'id' and 'rev' values, such as in the FileMetadata type as returned by /2/files/get_metadata, for instance.
In the documentation there, the 'id' field value is specified as 'String(min_length=1)' meaning it is a string at least one character long, but with no maximum length guaranteed.
Likewise, the 'rev' field value is specified as 'String(min_length=9, pattern="[0-9a-f]+")' meaning it is a string at least nine characters long, but with no maximum length guaranteed.