Why a specific armed forces board?

Hi all,

Just needed to see if anyone has advice for us, my boyfriend is South African and in his SA passport holds a stamp with says his exempt to immigration law whilst in the army. We have booked a holiday to spain in june and when filling out an application for getting a shengan visa it asks for a residents permit number (which a normal person gets in their passport whilst living and working here legally), which he hasnt got because of this stamp. Does this mean we will be refused? And what can we do to stop this/help ourselves so he doesn't? Has anybody else been through this?

Thanks

p.s. he cannot get a british passport thanks to the army sending him to germany for 5 years which according to the government doesn't count as being in this country!!!!