This is the official manual for the latest Org-mode release.
:tangle header argument specifies if the ‘src’ code block is
exported to source file(s).
tangleExport the ‘src’ code block to source file. The file name for the source file is derived from the name of the Org file, and the file extension is derived from the source code language identifier. Example:
noThe default. Do not extract the code a source code file. Example:
:tangleheader argument. Org derives the file name as being relative to the directory of the Org file's location. Example: