EMS physical page
Just as EMS object handles use logical pages indexed from 0, EMS Physical Segments are also numbered from 0. A particular address that can have expanded memory mapped into it can be referred to either by the address of a physical segment or by a physical page number. These are two alternate ways to refer to the same location in the 8086 addressable space. By convention, physical page 0 is the beginning of the mappable window and succeeding physical pages occupy contiguous pages in the window. Mappable physical pages in conventional memory (<640KB) follow the mappable window in this numbering scheme. Note that in EMS terminology a "physical page" does not mean physical memory; it is a way to refer to a particular address below 1MB.