Should you find your new profile does not do what you want it to then here are some things to check.
If it does nothing
Check the declaration of the CODE plugin is exactly like this:
{CODE(caption=>YAML)}
[your YAML goes in here]
{CODE}
Note: there must not be quotes around YAML and the ">" after the "=" is required.
If you get a "Profile cannot be parsed" (or whatever it says - TODO check) or blank page (sometimes)
Indentation matters and it has to be consistent in a "code block" Check the indentation carefully and compare yours with working profiles. It has to be very precise. It actually doesn't matter the amount of spaces (can be 1 space, 2 or 10) but each "level" has to be indented with the
same amount of spaces.
Applying some YAML on the fly
Sometimes, you just want to test that a particular section of the YAML is working, without having to go through the whole profile installation routine again.
A useful tool for doing that is the
Profile_Tester profile. If you install that profile on your test site, then in the Admin > Profile page, you will see at the bottom a text field where you can copy and paste some YAML.
Use with care, and only on tests sites!