Explained some of the 'magic numbers' for rectangular sign widths
drwxr-xr-x - example_signs
-rw-r--r-- 1738 length.xsl
-rw-r--r-- 13240 roadsigngen.xsl
drwxr-xr-x - svg_snippets
-rw-r--r-- 4254 transport_medium_widths.xml
-rw-r--r-- 3936 widths.xml