A ROMset is a specific collection of game ROMs that are audited to work with a specific version of MAME. You cannot easily mix and match.
A "Full Set" of 0.139 usually includes several gigabytes of data categorized as follows: : The core game code extracted from arcade chips. CHDs (Compressed Hunks of Data) mame 0139 romset
For users, 0.139 became the default standard for "MAME4droid" (the Android port) and early Raspberry Pi builds (like RetroPie 3.x). Because hardware was slower back then, 0.139 offered the best balance of accuracy and speed. A ROMset is a specific collection of game
"Romset is incorrect for this version of MAME." mame 0139 romset