Textfile - Tag - supporting all characters?

Is there any format of multi-field text file that allows all printable character sequences (including the field separator character) in a field, that this function will accept?

For example, CSV allows the field separator through double-quoting the field, and doubling any doubl-quotes within. But as far as I can tell, the Convert format string does not support this.

(I am writing a program to output from string fields in a database to a textfiles for Convert to import, and want it to work properly regardless of the string content.)