regopen
un->un_exclopen, flag, un->un_ocmap.regopen[otyp]);
if (un->un_ocmap.regopen[i] & (partmask)) {
un->un_ocmap.regopen[otyp] |= partmask;
un->un_ocmap.regopen[otyp] &= ~(1 << part);
un->un_exclopen, flag, un->un_ocmap.regopen[otyp]);
if (un->un_ocmap.regopen[i] & (partmask)) {
un->un_ocmap.regopen[otyp] |= partmask;
un->un_ocmap.regopen[otyp] &= ~(1<<part);