{ Situations leading to \\{midline} ... } = skipblanks+mathbr, skipblanks+tabmrk, skipblanks+macprm, skipblanks+supmrk, skipblanks+submrk, skipblanks+letter, skipblanks+otherchar, newline+mathbr, newline+tabmrk, newline+macprm, newline+letter, newline+otherchar { a } += alpha, {b}+=beta, {a}+=gamma, {b}+=delta, {a}+=epsilon, {b}+=zeta, {a}+=eta.