Items: Guidelines

Item Identifiers

Processing of Item Identifier points works in the following manner:

  1. The first character of the point value is checked when the point value is received.

  2. If the first character:

Is not $

The point is expected to contain the configured identifier and that Item is searched for and moved.

Is $

The rest of the value is checked against the reserved words.

If the rest of the value is:

Found to be a reserved word

The corresponding action is taken

Not found to be a reserved word

The rest of the value is taken as an Item Type ID and processing continues as if an Item Type detector was activated.

  1. If an Item identifier or Item type identifier is set and the Item cannot be found, an Item with that ID, reference ID or type (as appropriate) is created.

Currently, the only reserved word is TMOUT, and the action taken is to ignore the point.

An automatic item identifier is equivalent to a user transaction or an application interface message, in that it provides PRT with positive unique identification of the item.

If more than one entry transition indicator feeds a tracking region, items are stored in the region in the order in which the entry transition indicators are received by PRT.

More information

1. Items: defined.