The redshift catalog data in DR1 is about 0.1TB. Currently, there are v0 and v1 versions of the data, and the higher - version data is generally recommended. The v1 data, which is the latest version, consists of 51 files divided into four categories: zall-pix-SPECPROD.fits, zall-tilecumulative-SPECPROD.fits, zpix-SURVEY-PROGRAM.fits, and ztile-SURVEY-PROGRAM-GROUPTYPE.fits.
The ztile catalog includes redshifts for each survey and program combination. These redshifts are fitted to coadded exposures of individual tiles, not across tiles. The zpix catalog is similar to the ztile catalog, but it coadds data across tiles before redshift fitting. The zall-pix and zall-tilecumulative catalogs stack various zpix and ztile files into comprehensive catalogs that span all surveys and programs. For analyses focusing on the "best" redshift for a given target regardless of the survey or program, it is recommended to use the zall-pix and zall-tilecumulative catalogs.