The D100 value represents the diameter of the coarsest particle (in microns) which will pass through the screen during a dry laboratory test and is a single number, not a range of sizes.
The API screen designation for a screen is the API-defined range of sizes into which the D100 value falls. Some of the coarser size classes span quite a large range of D100 values. 

The D100 value is the finest particle diameter at which the screen no longer sends 100% of the particles to the discard stream. This is also the coarsest particle that will pass through the screen.
The D50 value is the particle size at which the screen sends 50% of the particles to the “overs�(discard), while the remaining 50% report to the “unders�(undersized stream) and the D100 should not be compared in any way. The D50 was interpreted as the micron size where a screen makesa 50/50 split.
The API RP 13C D100 is a very specific value determined from a carefully-controlled laboratory procedure so that any laboratory should measure the same value for any given screen cloth. 

Yes, more than half of the particles that are coarser than D50 and finer than D100 will report to the overs. A significant portion of the particles finer than D50 will also report to the unders. (By definition, every particle classified in the D100 size or coarser will report to the overs as expected.)

The biggest variation is due to the shift from the D50 value to the D100 value.
The previous test procedure for screens, API RP 13E, measured the distribution of the screen holes as measured by light, not solids. Subsequently, the screens were labeled using the D50, D16 and D84 separation curve.
The current test procedure, API RP 13C, measures the coarsest particle which passes through the screen, using a much more accurate and repeatable test method. The screens are now labeled using the D100 size criteria. 

PMD screen is the corrugated shaker screen with more effective filtration area. It really benefits much on shaker performance during solids control. Some clients comment, the pyramid shaker screen seems shorter life. Please do remember, when we utilize the PMD screen panel we have to decrease the shaker deck angle. If possible, we kindly suggest combine flat panel and PMD panel together on one shaker. Put the flat ones at solids discharge end. This will help much to save PMD screen life and, achieve higher efficiency than all flat panel fit on shaker.