Help me decipher this hair formula abbreviation

[lavendersky11]

Hi everyone! I found this old piece of paper with a hair dye formulation that I got at Aveda once. I'm not a professional, but at this point, I've been trying to experiment at home with dyes from Sally's because I don't have much money to spend for salon color. But I'm just curious, if I ever decide to go back to Aveda, what does the "Lt. Y/O" part of the formula mean?

Retouch formula:
40g 20 vol
40g 7N
2g Lt. Y/O
30 min. - start in front

[Janineb]

No idea I'm afraid. Not many of us are professionals either, so I'm not sure you'll get help unfortunately.

[Nickki]

I've had a quick scoot online and looks like it could mean Light Yellow Orange ?

They have a lot of products marked as Lt Y/O relating to light yellow orange and some marked as Dk Y/O which seem to relate to dark yellow orange.

[lavendersky11]

Okay, that makes sense! Thanks so much for your help!