Seminal Mnemonic and Leitmotif

WorNet 2.1 defines a Mnemonic as a device, such as, a rhyme or acronym used to aid recall.

Mnemonics connotes a method - a way of doing something, especially a systematic way, implying an orderly logical arrangement, usually in steps - to aid the memory, that is, in remembering (Ranganathan, 1967).