Versatile crate storage locations in a robotic-based storage system

A system comprising:

• a shelving block that comprises at least a first shelving unit and a second shelving unit, the first and second shelving units facing from opposite sides of an aisle, each shelving unit having a plurality of vertically spaced apart crate storage locations;
• a plurality of intersecting vertical and horizontal tracks, each track comprising a pair of parallel rails, a first rail of the pair located on the first shelving unit and a second rail of the pair located on the second shelving unit, a distance between the first rail and the second rail is in match with a distance between rail wheels of a robot intended to carry crates into or from said crate storage locations, wherein the robot is configured to carry crates according to instructions from a computerized control of the system;
• wherein the first shelving unit defines a first crate storage location and a second crate storage location, wherein the first crate storage location is accessible to the robot between a pair of neighboring horizontal rails having a first vertical spacing between them defining a height of the first crate storage location, wherein the second crate storage location is accessible to the robot between another pair of neighboring horizontal rails having a second vertical spacing between them defining a height of the second crate storage location, wherein the first vertical spacing is larger than the second vertical spacing, thereby defining two crate storage locations that differ in height.