get.refentry.source — Gets source metadata for a refentry
<xsl:template name="get.refentry.source"> <xsl:param name="refname"/> <xsl:param name="info"/> <xsl:param name="prefs"/> ... </xsl:template>
The man(7) man page describes this as "the
    source of the command", and provides the following examples:
    
For binaries, use something like: GNU, NET-2, SLS Distribution, MCC Distribution.
For system calls, use the version of the kernel that you are currently looking at: Linux 0.99.11.
For library calls, use the source of the function: GNU, BSD 4.3, Linux DLL 4.4.1.
The solbook(5) man page describes
    something very much like what man(7) calls
    "source", except that solbook(5) names it
    "software" and describes it like this:
    
This is the name of the software product that the topic discussed on the reference page belongs to. For example UNIX commands are part of the
SunOS x.xrelease.
In practice, there are many pages that simply have a version
    number in the "source" field. So, it looks like what we have is a
    two-part field,
    Name Version,
    where:
    
product name (e.g., BSD) or org. name (e.g., GNU)
version name
    Each part is optional. If the Name is a
    product name, then the Version is probably
    the version of the product. Or there may be no
    Name, in which case, if there is a
    Version, it is probably the version of the
    item itself, not the product it is part of. Or, if the
    Name is an organization name, then there
    probably will be no Version.