Album.sortTags argument ignored

[nbpf]

I think that the sorting works as expected but that I need to assign a default value for the "incdate" tag. Many albums have no "incdate" value and thus those that have one come up (sorted correctly) at the end of the list. How can I assign a default value, say "1974-01-01" to those albums that have no "incdate" values? Thanks, nbpf