A database record is the basic building block of an XPAC reserve database (often referred to as the main database) and stores the quantity and quality data relating to a single reserve unit. As mining reserves usually contain thousands of reserve units, XPAC reserve databases typically contain thousands of records.
Each record has a user defined set of data fields, where the data relating to the associated reserve unit is stored. A database can only have one set of data fields and every record must use this set.
Although records can be created manually, it is more common to allow XPAC to generate them automatically, during the data import process. This not only creates the records with the associated data, but also creates the hierarchical relationships between each record. When records are created manually, the user must indicate where each new record fits in the hierarchy. It is also possible to create records from within an XCM using a special function.
Although XPAC only stores the data relating to reserve units, it can calculate the accumulated values at higher levels of the hierarchy. To facilitate this process, XPAC creates records for the levels above each reserve unit, where it stores the results of the accumulations.
Consider a reserve unit in an open pit coal mine that represents Cut 3 of Strip 2 in the North Pit. Three records are required to store this reserve unit; namely one to represent the reserve unit itself, i.e. Cut 3, plus one to represent the North Pit and one to represent Strip 2 in the North pit. Only the Cut 3 record will contain actual data with the other two containing accumulated totals calculated by XPAC.
The records that contain data are referred to as Lowest Level Records, because they represent reserve units that are not subdivided any further and they have no records below them in the hierarchy. The remaining records that contain accumulations calculated by XPAC are called Upper Level Records, because these are subdivided further and do have records below them in the hierarchy. Because XPAC calculates the values of upper level records, data cannot be written to them directly. They can be read like normal records, however, thus allowing the database to be analysed at different levels of accuracy.
Because reserve units do not all occur on the same hierarchical level, lower level records do not always occur on the lowest defined level in the database. New reserve extensions at operating mines often fall into this category when there is insufficient sampling data to fully subdivide the extension in a similar manner to the main deposit. In this instance a reserve unit may be created to represent the entire extension, with a corresponding record on the first level of hierarchy. But although this record is not on the lowest defined level in the database, it is still a lower level record because it has not been subdivided further and will not have any records below it in the hierarchy.
XPAC uses the structure tree to view the records in a database, which works in a similar way to the directory tree in Windows Explorer (upper level records behave like directories and lower level records behave like files). The structure tree forms part of each database window and in conjunction with the level tree, controls what data is displayed in the database window's data sheet. It is expandable and collapsible, allowing the user to hide unnecessary portions when selecting a single record.
Database records have a number of means of identification as listed below: