Sheet package including side parts for a printer

A sheet package to be set in a sheet storage unit of a printer for supplying the printer with sheets, comprising:

• a stack of sheets;
• and
• a package member covering the stack of sheets, wherein:
• the sheets are supplied from the sheet package to the printer along a sheet feed direction,
• the package member has a side part, the side part including a portion that is attached to the package member at a first position and is separated from the package member at a second position, the side part being in parallel with the sheet feed direction and having a front edge and a rear edge relative to the sheet feed direction at the second position,
• the side part is structured such that the front edge contacts with a projecting part formed in the sheet storage unit in accordance with placement of the package member in the sheet storage unit relative to the sheet feed direction, and includes at least a first part and a second part,
• the sheet package includes a fold-back part to be folded back in order to expose part of the stack of sheets,
• the fold-back part is structured to be foldable by removing the one of the first part and the second part of the side part at a perforated line,
• the projecting part formed in the sheet storage unit is a pressing member which presses a side face of the stack of sheets so as to align the stack of sheets in a direction orthogonal to the sheet feed direction, and
• the pressing member is placed in a concave part formed on a side wall of the sheet storage unit corresponding to the side part, being pushed by a pushing member in the concave part so as to project from the concave part and press the side face of the stack of sheets.