I'm pretty green at this, but if you're accessing the XMP via extendscript, this has worked for me with PSDs:
if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");
I'm pretty green at this, but if you're accessing the XMP via extendscript, this has worked for me with PSDs:
if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");