A/ If you look carefully at the label that is stitched in when the strap is manufactured it will have information similar to this:
MBL 800daN - Minimum Break Load
LC 400 daN - Load Capacity
EN 12195-2 - Manufactured to EN Specification 12195-2 (Do not buy or use ANY straps that do not have this in. If you are using straps for commercial use and they are a BS specification, they are no longer legal.
PES - Polyester Webbing
Elongation < 7% See table below- Taken from "Analysis of Elongation of lashing straps on movements of cargo"
SHF 50 daN - Hand Force
"Not for Lifting"