The members of DocExComment_ExternalHyperlink(Rctfv) structure are as follows:
ident   Specifies the constant value, msodocexsignature, which identifies this EMF
comment as containing semantic information.
iComment   Specifies the MSODOCEXCOMMENT value,
msodocexcommentExternalHyperlink or msodocexcommentExternalHyperlinkRctfv.
rcdvRegion and rctfvRegion   A union that specifies the region of the page that is
the source location of the hyperlink. The region can be represented as a RECT type
(rcdvRegion) that uses device pixels as the unit of measure, or as a structure that
contains floating-point coordinates (rctfvRegion), in which case the unit of
measure is points.
If the iComment member is equal to msodocexcommentExternalHyperlink, the
add-in should use rcdvRegion. In this case, the add-in needs to apply the current
EMF transformation matrix to rcdvRegion to convert it to the page space.
If the iComment member is equal to msodocexcommentExternalHyperlinkRctfv,
the add-in should use rctfvRegion. In this case, rctfvRegion is already in the page
space, so no transformation is needed.
wzLink[MAX_PATH]   Specifies the destination URL for this hyperlink.
The DocExComment_InternalHyperlink(Rctfv) structure describes a hyperlink that links
to a location within the document. Note that, although Publisher passes a separate EMF
struct DocExComment_ExternalHyperlink
{
    DWORD ident {};
    DWORD iComment {};
    union
    {
        RECT  rcdvRegion;
        struct
        {
            float xLeft;
            float yTop;
            float dxWidth;
            float dyHeight;
        } rctfvRegion;
    };
    WCHAR wzLink[MAX_PATH];
};
DocExComment_InternalHyperlink(Rctfv)