I didn't think the .ps1xml, .psc1, or .psd1 files actually contain power shell source code.
.ps1xml is XML " The Types.ps1xml file in the Windows PowerShell installation directory ($pshome) is an XML-based text file..."
The sample .psc1 files look like XML.
.psd1 could be powershell code but the Wikipedia page says its a powershell data file. Sure doesn't sound like powershell code to me.