Citizenship and residence tags at present use the adjectival form. For example italian-citizens and italian-residents rather than [italy-citizens] and [italy-residents]. There are lots of citizenship tags:
afghan-citizens albanian-citizens algerian-citizens armenian-citizens australian-citizens austrian-citizens azerbaijani-citizens bahamian-citizens bangladeshi-citizens belarusian-citizens belgian-citizens bosnian-citizens brazilian-citizens british-citizens bulgarian-citizens cameroonian-citizens canadian-citizens chilean-citizens chinese-citizens colombian-citizens costa-rican-citizens croatian-citizens cuban-citizens danish-citizens dominican-citizens dutch-citizens ecuadorian-citizens egyptian-citizens eritrean-citizens ethiopian-citizens eu-citizens fijian-citizens filipino-citizens finnish-citizens french-citizens german-citizens ghanaian-citizens greek-citizens guatemalan-citizens guyanese-citizens haitian-citizens honduran-citizens hong-kong-citizens hungarian-citizens indian-citizens indonesian-citizens iranian-citizens iraqi-citizens iraqi-citizens irish-citizens israeli-citizens italian-citizens jamaican-citizens japanese-citizens jordanian-citizens kenyan-citizens kuwaiti-citizens kyrgyz-citizens lebanese-citizens libyan-citizens liechtenstein-citizens lithuanian-citizens macedonian-citizens malagasy-citizens malaysian-citizens maltese-citizens mauritian-citizens mexican-citizens moldovan-citizens mongolian-citizens moroccan-citizens mozambican-citizens myanmar-citizens nepali-citizens new-zealand-citizens nicaraguan-citizens nigerian-citizens norwegian-citizens pakistani-citizens peruvian-citizens polish-citizens portuguese-citizens romanian-citizens russian-citizens salvadoran-citizens saudi-citizens singaporean-citizens south-african-citizens spanish-citizens sri-lankan-citizens sudanese-citizens swazi-citizens swedish-citizens swiss-citizens syrian-citizens taiwanese-citizens tajikistani-citizens t-and-t-citizens thai-citizens tunisian-citizens turkish-citizens emiri-citizens ugandan-citizens uk-citizens ukrainian-citizens us-citizens uzbek-citizens venezuelan-citizens vietnamese-citizens yemeni-citizens zambian-citizens zimbabwean-citizens
and some residency tags:
australian-residents dutch-residents german-residents italian-residents uk-residents us-residents
The above may not be fully comprehensive but does indicate extensive use of the adjectival form. A very small number of the above are broken at present but have already been sent to the shop for repair (our master mechanic RoflcopterException is working on them).
For the country-specific Schengen visa tags however we have the locality form:
france-schengen-visas germany-schengen-visas greece-schengen-visas italy-schengen-visas netherlands-schengen-visa
The last being singular, despite Jeff's advice because it has hit the 25 character limit for a tag. (Mind you Dori, I think a CM at the time, was of a slightly different opinion.)
Change the country-specific Schengen visa tags to adjectival form and we could be consistent for both form and plurals (by choosing [dutch-schengen-visas]).
Is it worth it?