The "T" stands for "Transition," so named because it is often produced as Oceanside Glass and Tile shifts from one product to another in manufacture.
System 96 "T-Glass" is always 100% tested-compatible, devit-resistant, excellent-cutting, and otherwise top-performing fusible glass. It will, however, be outside of System 96's tolerances for surface texture, seeds, color hue, mix, or density.
Most surface imperfections will disappear in the fusing process. If you wish to retain them for effect, fuse at lower temperatures using shorter hold times. The more heat your project gets (the more "full" the fuse), the more an imperfect surface will heal.Avoid "T-Glass" where it is critical that you be able to replicate glass color from one project to the next.