As Chum Man said, the initial letters for Loomis are species or technique specific (BBR = back bounce rod, HSR = hot shot rod, SAR = salmon rod, STR = steelhead rod, SJR = spin jig rod, WJR = walleye jig rod, etc.). Then the next two or three digits are rod length in inches, followed by power rating. The power rating is subjective though, depending on the technique or species code. A one-rated salmon rod is heavier than a two-rated steelhead rod, etc. So you need to also look at the line rating, ask around, and just look through the catalog to get a feel for the different blanks.

Lamis are different and sometimes express the rod length in feet and inches, (106 is 10'6") but sometimes just have a number series like 1326T for a 9' salmon moocher with trigger handle, 1000 series graphite.

In other words... good luck!