User blog comment:Denis Maksudov/Fundamental sequences system for limit ordinals up to Large Veblen Ordinal/@comment-28606698-20170217215041/@comment-30118230-20170217221830

I don't see any but could you explain what the xi is used for in the line below the sentence "Fundamental sequences for limit ordinals of the theta-function up to Large Veblen Ordinal"?