Lexmark 4I3 - Manual (Page 283)

Weight
The basis weight for the paper should be 60 to 100 g/m (16 to 27
lb).
Composition
Plain bond paper of one of the following compositions should be
acceptable for regular use:
No. 1 sulphite (100% chemical wood pulp)
25% to 100% cotton content
Performance Considerations
For optimum performance:
Use 75 to 80 g/m (20 to 24 lb), 25% or 50% cotton content
plain paper.
Restrict printing to 6.35 mm (0.25 in.) from the left and right
margins and 6.35 mm (0.25 in.) from the top and bottom edges.
Keep at least three sheets in the selected input bin (paper load
failure frequency increases otherwise).
All input bins are capable of handling multiple-part forms.
Multiple-part forms present special considerations because of their
complexity. There are many different types of multiple-part forms
available. Use only snap-out or top-glued multiple-part forms on the
ASF. Form sets should be operationally tested before regular use.
For specific information about multiple-part forms, see IBM 4230
Printer Auto Sheet Feeder General Information.
Some forms such as highly embossed papers (many stock
certificates), coated papers, and multiple-part forms that do not
conform to specifications will not feed reliably by the ASF.
Forms are available from IBM or any forms supplier.
Appendix C. Forms Information C-5