we noticed that users' eyes were busy looking at th e storyboard, so they do not notice the updates to the Outpu t Display window . We expect that programmers would use this graphic tool t o make concrete the sequence of events underlying the sometimes mysterious nature of program execution . Whereas conventional debugging tools often leave programmers with an unsatisfying choice between viewing th e overall history of a high-level call and viewing a particula r time slice in depth, a two-dimensional graphic presentatio n can allow a programmer to see both views at once . As programmers' creations become more oriented t o graphics and multimedia, interactive techniques in programming will converge with those of multimedia. This research was conducted using a Hewlett Packar d workstation and was funded in part by Hewlett Packard an d Nynex . CONTACT INFORMATIO N user-written commands, full interoperability of text and graphical interfaces, a readily extensible set of object types , and a programming technique for decoupling graphica l display code from data maintenance code . The objectives of the OUI are: (1) A uniform and intuitive interface . The object-oriente d style has is appropriate for navigating databases of objects with spatial attributes . Only one interaction style is provided: select the object, then the operation, then give an y arguments . Less searching for a command is require d because commands are grouped by object type instead o f being lumped into a global namespace . New types of objects can easily be added to the system without alterin g the command interpreter. (2) Interoperability of text and graphical interfaces . Pointand-shoot interaction is natural for browsing geographi c information, but textual interfaces are superior for script driven use, command recall, session logging and wher e abstraction is needed, for example, "select all heritage site s matching *dale on this map " . The EDSS supports both textual and graphical interaction on a per-command basis . Every graphical command has a textual counterpart. (3) Programmability . The users of EDSS range from policy makers to database maintenance staff and styles of usage will vary so the EDSS must be customizable . Parameter settings must be accessible to the scripting language to control program flow . Different startup configurations can be arranged for each user. (4) Extensibility . We wish to avoid reinvention of existing software packages such as modelling programs and spreadsheets, so the ability to extend OUI by loosel y coupling external programs with a familiar syntax i s important . As far as possible, the invocation of an external program looks like that of a built-in command . CONTACT INFORMATIO N Michelle Fineblum, Research Assistant Henry Lieberman, Research Scientis t Visible Language Workshop MIT Media Laboratory, E15-44 3 20 Ames Street Cambridge, MA 02139 (617) 253-441 6 Fascimile : (617) 258-6264 e-mail : michelle@media-lab .media.mit .edu Lieber @ media-lab.media.mit. ed u AN OBJECT USER INTERFACE FOR AN ENVIRONMENTA L INFORMATION SYSTE M Ken Yap CSIRO Division of Information Technology, Australia The OUI is a graphical user interface developed for ou r Epvironmental Decision Support System project . The EDSS is a sophisticated browser and editor for environmental databases . Data held includes geographic data, text documents and pictures . The OUI explores these ideas : commands grouped by object type, a uniform interaction style for both built-in and Ken Yap Centre for Spatial Information Systems , CSIRO Division of Information Technology , GPO Box 664, Canberra, ACT 2601 , Australia Phone : +61 6 2750911 (GMT+10 ) 2750942 (direct line ) Fax : +61 6 257105 2 Email : ken@csis .dit.csiro .a u SIGCHI Bulletin October 1991 Volume 23, Number 4

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