Paper sizes, rolls and sheets, that are not a standard size offered by paper manufacturers and distributed by paper merchants.
As an example, a 17” x 22” sheet is a standard base stock size stocked by paper merchants. It would produce 4 sheets of a standard 8 1/2” x 11” cut sheet size.
If a non-standard cut sheet size of 8 1/4” x 10 was required, a non-standard base stock size of 16 1/2” x 20” would be needed to produce 4 sheets. Both the 8 1/4” x 10 cut sheet and the 16 1/2” x 20” base stock size are odd size sheets.
If an odd size sheet or roll is required, it may be more economical to use a larger standard size and dispose of the waste than to special order the odd size.