==> language/english/spelling/operations.on.words/movement.s <==
   longest word allowing exchange of letters (metallege) 
    CONSERVATIONAL, CONVERSATIONAL 
   longest head-to-tail shift 
    SPECULATION, PECULATIONS 
   longest double head-to-tail shift 
    STABLE-TABLES-ABLEST 
   longest complete cyclic transposal  ATE-TEA-EAT (3)
****
Unless noted otherwise, all words occur in Webster's Third New International
Dictionary, Merriam-Webster, Springfield, MA, 1961.