they are unhelpful because users tend to ignore them out of habit, and that having a universal undo eliminates the need for them. Universal use of text Raskin argues that graphic icons in software without any accompanying text are often cryptic to users. Habituation is an important concept driving Raskin's guidelines, intended to free the user's mind from attention to low-level interaction details. A modeless interface, monotony of design and elimination of blocking warnings are all intended to favor habit-forming reactions to interface handling. Non-standard interaction architecture Raskin also advocates a document-centered approach to computer interfaces that entails several radical changes to the current nature of operating systems and software: An end to stand-alone applications every software package should be structured as a set of tools available to users on any document. For example, in the middle of writing a text document, a user should be able to do a mathematical computation by writing out the computation in the document, then hitting some "calculate" function. An end to directories and file names "the content of a text file is its own best name." Every document should be identifiable by its contents, so there should not be need for directories or names for user-generated documents; Raskin argues that these names tend to be cryptic and make files difficult to find afterwards. Zooming user interface Raskin advocates an interface he calls ZoomWorld, in which the user navigates around a two-dimensional plane containing a graphical representation of every document on the computer. The user can zoom out to see all the documents, or zoom in on any specific document in order to read and edit it. Raskin further asserts that interface design should be subject to regulation, analogous to building codes. This could be done by establishing legal safeguards to protect consumers from harm, and establishing professional guidelines and standards to evaluate good practice and interface quality. Notes Sources External links Summary of design rules from The Humane Interface Jef Raskin User interfaces Computer books 2000 non-fiction books