ssub
sopno ssub; /* start sop of subsubRE */
ssub = ss + 1;
if (walk(m, sp, rest, ssub, esub, false) != NULL) {
dp = dissect(m, sp, rest, ssub, esub);
ssub = ss + 1;
sep = walk(m, ssp, rest, ssub, esub, false);
assert(walk(m, ssp, sep, ssub, esub, false) == rest);
dp = dissect(m, ssp, sep, ssub, esub);
ssub = ss + 1;
if (walk(m, sp, rest, ssub, esub,
ssub = esub + 1;
dp = dissect(m, sp, rest, ssub, esub);
sopno ssub; /* start sop of subsubRE */
ssub = ss + 1;
dp = backref(m, sp, stop, ssub, esub, lev, rec);
ssub = esub + 1;