This table is an associated to the GRBs Catalog and lists the parameters that define an 'irregular' region as the localization region. For a given GRB the localization can be provided by different observatories with different region types or by the same region type with different parameters. The different region types reported in literature are the following: circle, annulus, box, dual, annulus intersect, irregular, and intersect. This table contains the description only for the irregular region type, the other types are stored in separate tables. The 'irregual' region are from the Kippen et al. (1998). This localization region consist of a short thin arc segment derived from a COMPTEL localization combined with an IPN localization where the most likely position corresponds to the maximum obtained from the integral distribution. The COMPTEL localization consists of a circle error region centered at the most likely position within that region. The measurements are reported as found in literature and any differences or remarks are included in one of the table parameter (local_notes). The literature references are provided in the GRBs Catalog main table which is linked to this region table. This table was ingested by the HEASARC in June 2008 based on electronic versions obtained from the author(s), who compiled the catalog in 2005. This is a service provided by NASA HEASARC .