You might see these files when:
Many SEEPROMs have a CRC16 at the end. For example, a Broadcom-based router SEEPROM often uses a CCITT CRC over bytes 0..(N-3). Tools like seeprom-tools (open source) can verify this.
It sounds like you are referring to two binary files often found in embedded systems, firmware dumps, or hardware security contexts:
is a sector-by-sector image of this OTP region. Common sizes include 256 bytes, 1KB, or 4KB. This file contains data that is fused into the silicon during manufacturing.