7. Mindow-oriented types of information 
  
The following types of information have been introduced 
to administrate windows and annotate window-oriented: 
WHDR Window header 
WVT Vertex table 
WST Sub-window table 
WH History of analysis 
WS Statistical results 
WPT-SI Properties 
Once a window has been set up, a WHDR-records of about 
0.5 K bytes and a WH-record do exist while records of the 
remaining types of information may be created by 
succeeding analysis procedures. 
The function of WHDR-records is closely related to that 
of HDR-records though access to WHDR-records is not 
direct but depends on the way of referencing a window 
(cf. section 6). As many different WHDR-buffers have to 
be allocated, maintained and supplied by a program 
referencing PODIUM as there are different windows to be 
simultaneously worked. 
If the shape of a window is known this information may be 
optionally stored using WVT-records. The name vertex 
table associates the table containing a list of polygon 
vertices. This is not the case since such a list were too 
much influenced by analogous thinking and hence un- 
wieldly upon digital data management. Actually the 
structure of PODIUM's vertex tables corresponds to that 
of the so-called output tables (OT) discussed in /5/. 
The property tables provide a means of annotating window- 
oriented with respect to an image oriented table, called 
property definition table (PDT) and appertaining to ISO 
information (cf. section 5). The PDT completely lists 
the user defined properties for look up purposes and 
classifies them by subjects. Each individual window has 
its own property table which for each subject refers to 
at most one user selected property. This concept allows 
inquiring for the set of all windows 
- having one or any number of properties in common 
- or even having properties in common which are 
characterized by one or any number of subject sub- 
groups.