How to create a CALS table in Framemaker 2017

Here is my workflow:

1. Create a concept or reference topic
2. In Author or WYSIWYG view, click Insert table.
3. Specify a table geometry, say 3 columns by 6 rows.
4. Click the element dropdown: only simpletable is available as an option
5. Create the table. Switching to XML view, it is indeed a simpletable.
6. Back in Author view or WYSIWYG mode, select adjacent cells in the same row and merge (straddle them). Do the same for two adjacent cells in the same column. This seems to work, but
7. Switching to XML view and examining the table, it is still a simpletable, and all Framemaker did was delete stentry elements from strows.

I see discussion of CALS tables in the Help, but no description of how to create them.

Coding them by hand in XML view is not an appealing option. Can someone explain what I'm doing wrong?

Thanks