The Common Attachment document is an XML schema that contains default fields for mapping change request form values from one system to another. The common attachment format mirrors what one would see in an ITIL view of an Attachment form with related lists expressed in embedded XML form.
A sample Common Attachment looks like this:
<common_attachment>
<compressed/>
<content_type/>
<data/>
<file_name/>
<length/>
<position/>
<size_bytes/>
<size_compressed/>
<table_correlation_display/>
<table_correlation_id/>
<table_name/>
<table_number/>
<table_sys_id/>
</common_attachment>