The processing level designations can be found in the metadata (.MTL.txt) or processing history (WO.txt)* files that are delivered with Level-1 data products.
The MTL.txt file is included when data is processed through the Level-1 Product Generation System (LPGS). All Landsat 8 (2013-present), all Landsat 7 ETM+ (1999-present), most Landsat 4-5 TM (1982-present) and all Landsat MSS 1-5 (1972-1983 and 2012-2013) data are processed through LPGS.
*The WO.txt file is included when a scene is processed through the National Land Archive Production System (NLAPS). Some Landsat 4-5 TM (1982-1990) scenes are processed through NLAPS. Descriptions of processing levels can be found on the Landsat Processing Details page.
Within the MTL.txt file for each Pre-Collection and Collection 1 scene, the processing level is listed as DATA TYPE, as seen in Figure 2 below. Processing level designations differ between Pre-Collection and Collection 1 Landsat data, as shown in this graphic:
Figure 1. Pre-Collection and Collection 1 Processing Levels
Figure 2. Left: Pre-Collection Processing Level designation in metadata file. Right: Collection 1 Processing Level designation in metadata file.
Within the WO.txt file, the processing level is listed as Processing Level, as seen in the example below. Precision Geocorrection designates terrain corrected processing, similar to L1T processing in the MTL.txt file. Systematic Geocorrection designates systematic corrected (L1G) processing.
Figure 3. Processing Level designation in NLAPS-processed Work Order