[DFDL-WG] Can I ignore data I don't want in DFDL?

Suppose I am using DFDL to parse email headers. Suppose the RFC only allows 3 headers: To, From, Subject. DFDL can handle this, no problem. But suppose I get an email that includes a 4th header, one I have not planned for (i.e., have not included in the DFDL schema), don't care about, and don't want in the infoset. Like so: From: <john@doe.com> To: <jane@doe.com> Keywords: sales <-- this line should be ignored! Subject: Latest sales figures Can DFDL handle this? Does it have a mechanism for allowing me to ignore (and thus drop) data I haven't planned for and don't care about?