'Class A' Uniform - What is it?

What is a 'Class A' Uniform? (Boy Scouts of America calls these uniforms 'Field Uniforms'.)

Our Troop considers all of the following uniform pieces to be part of the Full 'Class A' Uniform: --Tan BSA Uniform Shirt, --Green BSA Uniform Pants or Shorts, --Green Webbing Belt, --Green Uniform Socks, --Merit Badge Sash, --Green & Yellow Neckerchief with Slide, --Red Troop Hat, --Rope Segment (hanging from belt or belt loop). This uniform should be worn on: --all Outings that require travel, --Community Service, --the 1st Troop Meeting of each month, & --all Courts of Honor.