*\input acphdr[v2,dek]
 (acphdr.TEX[v2,dek] 1 2
! Improper code.
<to be read again> 
                   \↔
p.2,l.3 \chcode'27123 \def↔
                           {\ifmmode{\mathrel{\char'444}}\else{\penalty999\ } }
↑e