Form and interface criteria 2.1. Clarity and functionality of interface, user guidance, availability of additional help. Availability of text-based interface. Technical criteria 3.1. Technical functionality of links in the materials, i.e. do they take you where they say they do or are the links old.
Functionality is tested three times at set intervals.
Unless the links work sufficiently well the third time, the material may be omitted. A verbal quality estimate is accompanied by information about whether there is a user fee and also about how and who can obtain user rights. References About EELS . Selection criteria for Internet resources. NetFirst frequently asked questions .