N-X-L nomenclature, introduced collaboratively by the research groups of Martin, Arduengo, and Kochi in 1980, is often used to classify hypervalent compounds of main group elements, where:
* N represents the number of valence electrons
* X is the chemical symbol of the central atom
* L the number of ligands to the central atom
Examples of N-X-L nomenclature include: 
* XeF, 10-Xe-2
* PCl, 10-P-5
* SF, 12-S-6
* IF, 14-I-7