X\(tsX \\(ts terminal sigma
X\(rnX \\(rn root en extender
X\(==X \\(== identically equal
X\(~=X \\(~= approximately equal
X\(apX \\(ap approximates
X\(caX \\(ca cap (intersection)
X\(ibX \\(ib improper subset
X\(ipX \\(ip improper superset
X\(pdX \\(pd partial derivative
X\(isX \\(is integral sign
X\(ptX \\(pt proportional to
X\(brX \\(br box vertical rule
X\(ddX \\(dd double dagger
X\(bsX \\(bs Bell System logo
X\(ltX \\(lt left top of big curly bracket
X\(rbX \\(rb right bottom
X\(lkX \\(lk left center of big curly bracket
X\(rkX \\(rk right center of big curly bracket
X\(bvX \\(bv bold vertical
X\(lfX \\(lf left floor (left bottom of big square bracket)
X\(rfX \\(rf right floor (right bottom)
X\(lcX \\(lc left ceiling (left top)
X\(rcX \\(rc right ceiling (right top)