extra chars and mask files

Given this set-up to include some extra German characters:

./oclHashcat64.bin -m 7900 -1 äöüß?l -2 ÜÄÖ?u -3 €?s -a 3 --increment hashes.txt rockyou-7-2592000-copy.hcmask

I could simply use one of the rockyou mask files by making a copy and doing a simple find & replace to switch out:
1 for l
2 for u
3 for s

Correct ?