The object truncatedCanonicalSeries (missing documentation) is a method function.
The source of this document is in /builddir/build/BUILD/Macaulay2-1.25.05-build/M2-release-1.25.05/M2/BUILD/x86_64-redhat-linux-gnu/Macaulay2/packages/HolonomicSystems-temporary/currentString:1:439.