From UFStarfleet Wiki
In stellar cartography a Sector Block is an area of space containing 25 sectors. Near the UFP in the Alpha Quadrant, and near Pinastri in the Delta Quadrant sector blocks are almost exactly 100 light-years cubed. The Image below shows the mapped Sector Blocks in and around UFS space.
By comparing the image below with the Delta Quadrant Sector Map you can see that the Pinastri Sector is located in Sector Block Delta 01, whereas the Racladi Sector for example is located in Sector Block Delta 09