Any reference file in PDF, JPG or PNG format with description of your requirements would be enough. If you have an idea or concept drawing, the easiest way to convey your requirement would be through a hand drawn sketch • Block Flow Diagram (BFD) • Process flow diagram (PFD) • Utility Flow Diagram (UFD) • Piping and Instrumentation Diagram (P&ID) • and any relevant work on Auto-CAD & smart plant pid