Custom layer entry — any key not in STANDARD_SLOTS. The presence of .layer discriminates this from a slot config.
STANDARD_SLOTS
.layer
Optional
Insert immediately after the named standard slot or another custom-layer key.
Insert immediately before the named standard slot or another custom-layer key.
Custom layer entry — any key not in
STANDARD_SLOTS. The presence of.layerdiscriminates this from a slot config.