Is SSJ3 a grade?

I was looking at the Super Saiyan grade forms, and I know that there are 5 grades (Grade 1 - initial SSJ form, Grade 2 - SSJ Second Grade aka Ascended Saiyan, Grade 3 - SSJ Third Grade aka Ultra SSJ, Grade 4 - Mastered SSJ, and Grade 5 - SSJ2, which was initially referred to as SSJ Fifth Grade).

So I then looked as SSJ3, which isn't referred to as Grade 6, so my question is if SSJ3 is also a SSJ grade, or is it separate like stuff like DBS Broly's form or SSJ Rage?