Epson TM-C3500 Series Technical Reference Manual page 210

Die-cut label (Blackmark)
<When removing all the fringes>
Paper width
Edge R
Label width
Edge cutoff
Center of black marks
Center of paper width
Perforation position
2 mm or more 
( W h e n u s i n g fa n -
fold paper)
210
Edge R
Edge cutoff
width
Edge cutoff
Edge cutoff
<Back side>
Black mark width
<When removing fringes on the left and right edges>
Paper width
Label part
Label width
<Printing side>
Center of paper
width
Backing paper
Label area
Edge cutoff
Paper feeding
direction
Backing paper
Label area