NEXTTAB
for (fr = from_x; (nxt = NEXTTAB(fr)) <= to_x; fr = nxt) {
NEXTTAB(descrlen) + sizelen, "Size",
NEXTTAB(sizelen) + usedlen, "Used",
NEXTTAB(usedlen) + availlen, "Available",
NEXTTAB(availlen) + proclen, "Used%");
NEXTTAB(descrlen) + sizelen, df[i].size,
NEXTTAB(sizelen) + usedlen, df[i].used,
NEXTTAB(usedlen) + availlen, df[i].avail,
NEXTTAB(availlen) + proclen, df[i].proc);