DT code: Confusing and problematic. Gibson uses it inconsistently across different models - and not just "standard" models ("Dual pups figured Top", that DT was on a thinline model with dual pups and a figured top - not a standard model). Gibson does use T to indicate figured Top - I have a 359 with a figured top designated in the model number with a T (ES359TVSGH1). Also, DT = DoT (vs. block) markers (that is from Gibson C/S), and yet DT also shows up on models with markers that are not dots. The same confusion exists for DP - Dual Pickups and Dot Plain-top
Some information about model numbers in the Gibson acoustic division -
CH code: I also own several Gibson acoustics as well as Gibson electrics, and have seen many model numbers. CH is used on acoustics and it means Chrome Hardware. Similarly Gibson acoustics use GH and NH for Gold Hardware and Nickel Hardware. Note the hardware code is 2 letters in all cases. As for electrics, here's a Sweetwater listing page for a '61 SG Standard Vibrola which lists the model number/manufactures part number as SG61V00VENH1 where NH is the code for Nickel Hardware, NOT Nickel, Hardtail. As for a hardtail - here's a Sweetwater listing page for 61 SG Standard (hardtail) which lists the model number/manufactures part number as SG6100VENH1, ending the same way. Seems Gibson is again using NH for Nickel Hardware, NOT Nickel, Hardtail. For acoustics as well as electrics, this makes using C for Chrome and H for Hardtail obviously problematic, and I'm not sure it is correct.
1 code: In 1985 Gibson stopped labeling seconds, but many model numbers still end in 1. It appears that Gibson acoustic reassigned the number for the hand - 1=RH, 2=LH, and 3=RH with pick up, and 4=LH with pick up. Sometime after 2014 Gibson Acoustic began to drop the ending digit from model numbers and designate left handed guitars by ending the model# with "L". I don't know what Gibson electric division uses the 1 for, but it doesn't indicate the hand.