'...&GAPCOSTS=12+2&...' will set the values
to 12 and 2, respectively.
Note: Only a limited set of values are acceptable for supported scoring
matrices. If not specified in the 'Put' URL, the default
'GAPCOSTS=11+1' will be used for blastp,
and 'GAPCOSTS=5+2' will be used for blastn.
See details on this setting in 6.13.