diff --git a/README.md b/README.md
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@@ -5,3 +5,14 @@ This makes use a lot of Unix system calls as well as a bash script to convert th
 
 Intended for use with the [yuzu Emulator](https://yuzu-emu.org/) project, but the project in the future likely won't ship synthesized Switch archives.
 That leaves this project in a place where it is not likely to be used, but will remain here as a reference.
+
+- tzdb: CMake and bash script to build and convert time zone data from https://www.iana.org/time-zones into the Nintendo Switch's format.
+- tzdb2nx: C++ program that converts a single tzif file to the Nintendo's format.
+
+The fine folks over at [SwitchBrew](https://switchbrew.org/wiki/PSC_services#ITimeZoneService) have left very helpful information on reading the data.
+Nintendo's file is simply the TZif version 2 data, with standard_indicators and ut_indicators data stripped out (and the necessary modifications needed in the header to make the data valid).
+This means the TZif 1 data is not present, so essentially we are left with the second half of each file.
+
+Nintendo also does not seem to run the `zic` program on their output when they build the time zone data.
+I have left the relevant build command for that in src/tzdb/CMakeLists.txt commented out, but it isn't used here.
+This lets the project produce data identical to Nintendo's firmware for time zones, however this code does not produce the time zone data on US/Pacific-New or America/East-Saskatchewan (I may have bunged up the actual paths for these as this is 3 day old memory).