Engineering quotations are rarely a single price. They are a build-up of materials, labour, subcontract and margin, revised several times before an order arrives - and the revision that was actually accepted needs to be the one the job is costed against.
The system holds quotations as structured line items rather than a document, so a revision is a new version of the same enquiry rather than a separate file with a slightly different name. Approved quotations become jobs, and jobs carry their costs forward, so the comparison between quoted and actual is available without rebuilding it in a spreadsheet.
PDF output matches the company's own quotation format, because the document a client receives should not look like it came out of a generic tool.