Quote:tStop - Top side solder mask - This defines where soldermask should NOT be. Otherwise soldermask will cover the whole PCB.
bStop - Bottom side solder mask - This defines where soldermask should NOT be. Otherwise soldermask will cover the whole PCB.
https://www.worthingtonassembly.com/eagle-layers
http://docs.oshpark.com/design-tools/eag...explained/