Epson TM-T88 Series Technical Reference Manual page 86

Thermal paper specifications
When using thermal paper, the paper must meet the following conditions:
Non-printing side
• Black marks or similar marks are NOT printed on the back (non-printing side)
• The reflection rate of prohibited preprint area is 70% or more
Note: Reflection rates are measured by the Macbeth PCM-II (Filter D). The back of the paper is measured.
Prohibited preprint area
Paper feed direction
15.0 {0.59"}
Permitted preprint area
Paper width 57.5 ± 0.5 mm {2.26 ± 0.02"} or
79.5 ± 0.5 mm {3.13 ± 0.02"}
Units: mm
Back (non-printing side)
86