This is a C macro that expands to a string with the version of librsvg against which your program is compiled.
For example, for librsvg-2.3.4, this macro expands to
C programs can use this as a compile-time check for the required version, but note that generally it is a better idea to do compile-time checks by calling pkg-config in your build scripts.
Note: for a run-time check on the version of librsvg that your
program is running with (e.g. the version which the linker used for
your program), or for programs not written in C, use
Available since: 2.0