Contract Purchase Agreement standard practice for Contract Purchase Agreement PO print

when a buyer creates a Contract Purchase Agreement, what is the standard practice for creating the contract language?  Does the buyer use header text attachments marked "to supplier" to create the contract verbiage on the CPA PO print?  We have found that any header text attachments will then print on the releases with every line, along with the standard verbiage "this line refrences Contract Agreement #####".  For example, a CPA may be created for office supplies, the CPA document will contain the contract verbiage in supplier text attachments, which can be lengthy.  We use this as the contract document for