Readers will be familiar with assigning A=1, B=2 though Z=26 to find the letter total of a word. Most of the words in this article can be found in the OED Second Edition. dfpf = A Dictionary of the Flowering Plants & Ferns, CUP 1966. Clafouti (cherry flan) can be found in recipe books.
"Numerically Equivalent Letter Replacements,"
Word Ways: Vol. 34
, Article 17.
Available at: https://digitalcommons.butler.edu/wordways/vol34/iss4/17