Action type constants for TP-Link router commands.
These values specify the operation type when constructing actions:
GET(1): Retrieve dataSET(2): Modify dataADD(3): Add new entryDEL(4): Delete entryGL(5): Get listGS(6): Get/Set combined operationOP(7): Execute operationCGI(8): CGI script execution
The constants are dialect-neutral: each dialect maps them onto whatever its
firmware expects (decimal digits for gdprText, go/gl/cgi strings for
gdprJson).