I.R.I.S. Readiris Pro 12 for Windows User Guide - Manual (Page 97)

Readiris TM Pro 12 – User Guide
91
 Use a sufficiently thick ballpoint.
Black pens yield better results than blue pens.
Do not use pencils.
 Don't stylize too much.
Excessively stylized characters increase the risk of OCR errors.
 Don't open loops which should be closed, don't close loops
which should be open.
 Avoid broken characters.
 Avoid retracing.
Retracing reduces the image quality and clarity of handprinted
symbols.
Characters that are entirely stricken out will not be recognized.
 Write ones correctly.
The number 1 can be written in the "anglicized" and "European" style.
Ones can be underlined or not.