Printing-fluid cartridge including contact surface for providing positioning of the printing-fluid cartridge

A printing-fluid cartridge comprising:

• a front surface;
• a rear surface away from the front surface in a rearward direction crossing a gravitational direction in an upright posture, the rear surface facing rearward in the upright posture;
• a storage chamber configured to store printing fluid therein and positioned between the front surface and the rear surface;
• a supply portion having a supply port through which the printing fluid is configured to flow out of the storage chamber in a frontward direction opposite to the rearward direction in the upright posture, the supply port defining a center in the gravitational direction;
• an upper surface positioned upward relative to the storage chamber in the upright posture and facing upward in the upright posture;
• a locking surface positioned upward relative to the storage chamber and facing rearward in the upright posture, the locking surface having an upper end in the upright posture;
• an electrical interface positioned upward relative to the storage chamber and facing upward in the upright posture, the electrical interface being positioned rearward relative to the supply port of the supply portion in the frontward direction in the upright posture;
• and
• a contact surface provided rearward relative to the supply port of the supply portion in the frontward direction and facing upward in the upright posture,
• the printing-fluid cartridge defining a rearmost point in the frontward direction in the upright posture, the locking surface being positioned closer to the rearmost point than to the supply port in the frontward direction in the upright posture, and
• the upper end of the locking surface being positioned farther away from the center of the supply port than the contact surface is from the center of the supply port in an upward direction opposite to the gravitational direction in the upright posture,
• wherein, in the upright posture,
• the contact surface is positioned rearward of the electrical interface and forward of the locking surface in the frontward direction;
• and
• the contact surface is positioned higher relative to the electrical interface and lower than the upper end of the locking surface in the upward direction.