.export

.export [label [, label [, label [, ...]]]]

This tells Brass to add a label name to the label export file. If you do not specify any label names, any named labels defined after that point will be exported.

.org $100
start_of_code:
    .dw $FAFF
end_of_code:
        
.export start_of_code, end_of_code

This would produce the following label export file:

start_of_code   .equ    $0100
end_of_code     .equ    $0102