High profile cone top - a conetop with a prominent "high" spout.
Humidity Spotting - Very common on metallic paint or finish when it gets a little bit of surface rust that make the paint look discolored or spotty. It usually won't clean up and it decreases a can's value.
Indoor cans - Cans that were found in a building. Normally these cans are in good condition
internal revenue tax paid - Cans of beer produced before March 1950 for sale in the US were required to indicate that the brewer had paid the necessary federal taxes. Some variation of the tax paid message appears on every can filled before March, 1950.
IRTP - abbreviation for internal revenue tax paid.
J-Spout - a conetop produced by Crown, Cork and Seal from 1937 to 1942, the j-spout has an elongated spout on its top.