This directory contains the Valve Half-Life SDK for HL1.
Below is a list of the files and their contents.

README.txt                      - This file.
hl_sdk_v23.exe                  - The original Full SDK v2.3 with client 
                                  development tools etc.
hl_sdk_v23_source.exe           - The original Standard SDK v2.3, i.e. only 
                                  sources and headers. Only the standard SDK
                                  is needed for Metamod plugin development.
hl_sdk_v23_source-update-p3.zip - A ZIP archive that can be extracted over 
                                  the original SDK v2.3 with updated files
                                  that were added/changed later by Valve without
                                  a SDK update.
hlsdk-2.3-p3.tar.gz             - The Standard SDK v2.3 with various fixes and
                                  updates, that Metamod is compiled against.
                                  Files are in Unix format.
hlsdk-2.3-p3.zip                - The Standard SDK v2.3 with various fixes and
                                  updates, that Metamod is compiled against.
                                  Files are in DOS format.
metamod.hlsdk-2.3-p3.patch      - A patch (diff) file against the original 
                                  Standard SDK v2.3, containing the changes made
                                  in the patched versions. File is in Unix format.
metamod.hlsdk-2.3-p3.txt        - Description of the various changes and updates
                                  made in the patched version.

The directories p<n> contain the files described above for version <n> of the
patch.

Please read the HL SDK License Agreement in SDK_EULA.txt before using the SDK.