Epson EPL-6100 Reference Manual page 158

Join
Allows you to define how the ends of lines should be joined. The
default setting is Mitered. See the illustrations below.
NONE
ROUND
Pen0, Pen1, Pen2, Pen3, Pen4, Pen5, Pen6
Allows you to select the line width. You can select a value from
0.05 mm to 5.00 mm, in increments of 0.05 mm. Pen3 to Pen6 are
available only in GLlike mode.
56 Using the Remote Control Panel Utility
MITERED
MITEREDBEVEL
BEVELED
TRIANGULAR