@SELECT requires a MySQL statement to pull a selection from the database. @DOCUMENT is much simpler, it’s just a reference to a document at the site (by document ID). With @DOCUMENT, the content field of the specified document replaces the TV tag.
Here’s a cool way to use @DOCUMENT. Let’s say the IDs of the featured houses are 1, 2,and 3. The Input Option values of the TV on the home page could look like this:
323 Maple==@DOCUMENT 1||213 Pine==@DOCUMENT 2||923 Elm==@DOCUMENT 3
Format the TV as a drop-down list or as radio options. The user will see this:
323 Maple
213 Pine
923 Elm
but the TV tag will be replaced by the @DOCUMENT part which will be replaced by the content of document containing the property the user selects.
If you really want to get fancy, you could actually use an @EVAL statement with runSnippet() and create a snippet that would generate the Input Option Values drop-down list from all the houses in a particular container (or tagged in some way -- e.g. with another TV called "Featured"). Of course, you could also rotate the featured houses at random. Is MODx cool or what?