**Steps to replicate the issue** (include links if applicable):
* Go to the REST Sandbox on test wiki: https://test.wikipedia.org/wiki/Special:RestSandbox
* Compare available routes and options to REST API reference documentation https://www.mediawiki.org/wiki/API:REST_API/Reference#Transform
* Click "Try it out" on `/transform/{from}/to/html/{title}`
* Enter:
* "wikitext" for from value
* "Earth" for page title
* Click "Try it out" on `/transform/{from}/to/html` (without title)
* Notice that there is no block where wikitext can be entered
**What happens?**:
* The routes do not match the reference documentation; "from" value must be populated by the user instead of pre-populating with 'wikitext'
* In cases where the user is expected to enter free text (either HTML or wikitext) there is no post body parameter where the data can be populated.
* Where the title/revision values can be used instead of free text, 415 - Unsupported Media Type Error is returned.
Note: These seem to apply for all endpoints in the Transform space.
**What should have happened instead?**:
* Post body options should reflect all possible fields.
* "from" should be populated within the route, per the reference documentation.
* Alternatively: consolidate to a single endpoint with supported options listed for to and from values
* The respective page transformation should be returned.
**Software version** (on `Special:Version` page; skip for WMF-hosted wikis like Wikipedia):
**Other information** (browser name/version, screenshots, etc.):