Aacute A+~acute.case
aacute a+~acute

From the FontLab forum:
“You'll find it in the "Creating Composites and Ligatures" section in the manual:

In the composition recipe, the "+" command may be followed by one or
two alignment commands:
^ align component to the uppercase position
~ do not move component vertically
< align component to the left of the base glyph
> align component to the right of the base glyph
| center component horizontally

[...]

Use "%=" instead of "=" to decompose created composite glyph. For
example:
A+^ring%=Aringdecomposed”

You won’t run into problems when opening the font on another computer.

Ohh these are codes to be used for the Generate Glyphs command. For some reason I missed that. Thanks for elaborating.

Two question which went unanswered: is it better to use .case, .cap or doesn't it matter as long as you're consistent? What's the appropriate name of the caron that looks like a comma?

alias.dat is used for generate glyphs, and also when you double-click on an empty slot in the font window.

.cap or .case doesn’t matter as long as there is the matching data in alias.dat. On a technical level, you could even use some of each, but that would probably get confusing!

I’d name it the alternate caron... caron + some extension. Could be caron.commalike or caron.alt.