In a 1967 article in Datamation, a simple set of rules were described for abbreviating variable names using mnemonics. Mnemonics aid in increasing the readability of programs by reducing the length of variable names. The article follows these rules:
1. Abbreviate every significant word in the name, up to a maximum of three words.
2. Initial letters must always be present.
3. Consonants are more important than vowels.
4. The beginning of a word is more important than the end.
5. Abbreviate to between 6-15 letters in all.
For example, “speed of light” becomes spd_lght.
 Jackson, M., “Mnemonics”, Datamation (1967).