(1978). On Facilitating Networks for Social Change ... - INSNA

- 23 -. . . Computer Programs, cont'dadd : To enhance the readability of the printer-output, to help the user in remembering what the dataelementsstand for and to document his GSF, the user of GRADAP is provided with the possibility of defininglabels for his system file, for the point and lineinfo's (and their values) and for the point andlinesets . Also DOCUMENT information may be added to the GRADAP system files, in the same way as in SPSS .The creation date and time of the GRAPH is another item of documentary information . When a point isidentified by a name and a label is present, the label is also purely documentary .Besides the above outlined information elements it may be possible that a matrix system will beadded to the GSF, in order to have graph-analytical matrices such as adjacency matrices and points-pairmeasure matrices stored together with their descriptive information and "parental" raw-data matrix .1 .2 Files1 . GRADAP System File : As mentioned in the previous section the graph data will be stored in aGRADAP system file (GSF) . Once defined and stored a GRAPH may be submitted to GRADAP in other runs forfurther analyses and/or modifications . The SAVE GRAPH instruction will cause the available graph informationto be written on a write-only file, with the default logical file name SVGRAPH (analoguous to theSPSS SAVE FILE procedure) . In the same fashion the control statement GET GRAPH will instruct GRADAP toread in a complete GRAPH (as saved in a previous run) from a read-only file, with the default logicalfile name GTGRAPH .2 . SPSS System files : To enable the user to submit to or to extract from GRADAP SPSS system fileswith point or lineinfo matrices, GRADAP must be able to read and write SPSS system files . The pointand lineinfo's will correspond to variables, the points and lines will correspond to cases while thepoint and linesets will correspond to subfiles .3 . Coded input files : Coded input to GRADAP will consist of the GRADAP control statements thatspecify the graph data in the definition phase or indicate the modifications to be made and instructGRADAP for the different analytical procedures . These control statements will be described in the nextsections . The graph data, when not specified in the control statements themselves, also constitute codedinput to GRADAP . They need not necessarily reside on the control statement file INPUT, but may reside onanother medium which is specified by an INPUT MEDIUM card (see section 3) . All coded input must be cardimage.4 . Coded output files : The coded output of GRADAP will consist of the run statistics and theresults of the analyses on the printer file OUTPUT and possibly of coded card-image output data ormatrices on an alternate output file, which will have the default logical file name BCDOUT . The dataand/or matrices on the latter file may be used as input for GRADAP, SPSS, STAP or other programs orpackages5 . Scratch files : Besides the above described files which may be controlled by the user (as far astheir existence outside the reach of GRADAP is concerned), GRADAP will internally use some scratch filesfor system data and intermediate results . These scratch files will have logical file names XXGRDn, wheren is an integer from 1 to 6 . They will be controlled by GRADAP and are returned to the operating systemat run termination .1 .3 Input/OutputFor the input/output software to be used in GRADAP, standard CDC software (Record Manager) should beused as far as possible . However, in order not to use too much IO-time, it may be necessary to usespecial 10 procedures to read and write the GRADAP system files and scratch files . The same goes for theSPSS system files, which are not Record Manager files to start with . These so-called "owncode" proceduresshould be well documented in order to reduce the amount of work necessary to maintain, update oreven transport the package to other installations .The GRADAP system files will be binary files, as their main purpose is to store the graph data in aneconomic way for future access by GRADAP . Furthermore, the conversion involved in reading and writing ofcoded data will form a too large overhead unnecessary for the internal use of these files . Of course,the SPSS system files are also binary files .2 . System and Graph DefinitionThe control language of the application package GRADAP - the concept of application language is usedhere according to Van Hoboken and Niemoller (1976) - consists of control statement . In these statementsall information can be defined, required for execution of the GRADAP system .The control statements start with a control field (cols 1-15) and have so-called keyword expressionsin the specification field (cols 16-80) . The language elements are control-words, keywords, identifiers,