HP Designjet T3500 Production eMFP - Manual (Page 243)

Alignment
Looking at patterns 4, 13, and 14, you may find problems with the printer’s printhead alignment, which can
cause defects such as the following.
Additionally, misalignment problems can be seen in patterns 4 and 9 in the form of color fringing (which is
exaggerated below, on the right). That is, the limits between two strong colors are not well defined or a third
color appears between them.
ENWW Visual check for errors while printing the diagnostic sheet 233