In the Jackson 5's early years at Motown Tony Jones, cousin of Suzanne DePasse, was put in charge of print publicity for the group, and part of his responsibilities included creating a public image for each boy. The following fact sheet was sent out to teen magazines to help jump-start their introductory articles on the group. I got it as part of a 16 magazine production lot I bought several years ago.
The sizing charts were most likely intended to help with wardrobe for photo shoots, although 16 and Spec both used to regularly print clothing sizes, as if they expected fans to go out and buy clothes for the stars.
Here's how the info Tony Jones sent out translated into teen mag speak: