Database Procedures Used to Create the Ceramic Distribution Maps

Modeling ceramic distribution was a complex process carried out in ARC/INFO. A graphical user interface designed to access the data was written in ARC/INFO's programming language, AML. The task of this program was to create distribution maps for pottery, based on user selected forms and archaeological periods. At the core of the process were two INFO programs used to provide total weights and counts for the selected ceramic form and period in each collection square from Tall Jalul. The first INFO program created a "subset" table from selected records. The second program created a summary table containing cumulative totals from items in selected records.

To create the subset table, a selection menu was written in AML which allowed the user to select an archaeological period which was then passed as a variable to INFO through another AML called INFORESEL. The INFO commands processed within INFORESEL are shown in Table 1. The "many" table of ceramic attribute data was the selected table, while an empty template of the subset table was the related table. The table (MANYPOTS) was SELECTed (Line 16), then RESELECTed according to the variable value passed from the selection menu (Line 17). The empty table, PSUBSET, was RELATEd with the APPEND option (Line 18).

The next active command created the file by appending one record per relate item to the subset table, automatically filling the related item's value. In this case, the active command which created the table was CALC (Line 19), which transferred the CNT value to the subset CNT item; the next CALC command transferred the WGHT value to the subset table's WGHT item.

Up to this point the INFO commands listed in the AML were processed as if they were executed interactively. This means that a single command processed all selected records. However, through INFO's PROGRAMming feature, it is possible to process several commands per record. The special processing feature of a PROGRAM is the ability to switch between processing one command for all records and processing multiple commands for one record; this switch is in the "odd" and "even" program sections.

The rest of this example demonstrates how a summary table was created, with one record per ID_NO, containing total CNT and total WGHT for the period. In Line 21, the command RUN TOTES started a program named TOTES in the INFO subdirectory (Table 2). This program SELECTed the previously created PSUBSET table and RELATEed an empty template table SUMCTWT in the odd program section ONE, where each command acts on all records. Then, in the even program section TWO, both CALC commands acted on the first related record. Processing continued to loop through both CALC commands in the even section (TWO) for each succeeding record until the end of table. The resulting summary-subset table SUMCTWT was used in GRID to create surfaces which model ceramic distribution at Tell Jalul. (Christopherson, Guertin, & Borstad, 1996)

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