I made some icons for the german definitions of access derived from the well known symbol of access for a website. Now I have multiple requests, if the symbols are free to use. I like to host them on github with an SVG source for other projects to use them. But on diving into the legal issues, I do not really know, if I can offer them for free use.
The original work is from Susanne Koefoed from 1968 and modified from Karl Montan 1969. Since 1984 it is part of the standard ISO 7001. According to the source on wikipedia, this icon is free to use:
But the templates I used from and with courtesy of http://www.mobidat.net/ seem to be from an derived work from the Graphic Artist Guild. This icon seems free to use but I did not find any copyright information on their website:
My set of symbols have slightly different proportions, do not have foots and a different angle for the legs. Here is the part of the derived work:
My question is, if or how I can publish a derived work of a derived free work for free use?