Writing long command lines every time you need to convert a document is boring and error prone. The Options setting let the user save all the converting options together with the source document. This also ensures that the document will always be converted the same way, with the same options.
Just write it with no syntax errors, as you were on the real command line. But omit the "txt2tags" program call on the beginning, the target specification and the source filename from the ending.
For example, if you do use this command line to convert your document:
$ txt2tags -t html --toc --toc-level 2 --enum-title file.t2t
You can save yourself from typing pain using this Options setting inside the document source:
%!target: html %!options(html): --toc --toc-level 2 --enum-title
Now the options are registered inside the source file, so you can convert it with this simple command:
$ txt2tags file.t2t
Tip for Vim users: To convert the document right inside the
editor, just run :!txt2tags %