GUIDs

IFC Export User Guide

GUIDs

Functionality is available to import several versions of an IFC model into an AVEVA E3D™ project. This might mean that there are several incarnations of the same elements sharing a GUID.

Having a set of GUID, rather than creating one each time the model is exported, means that there is a reproducibility of the export process, the element has the same GUID each time it is exported.

The main change to the design data model is to extend the application of the UUIDIA attribute to more elements.

The UUIDIA is added to the following elements, the elements highlighted in red are those that currently have UUIDIA from the IFC Import project. It is unreasonable to apply the attribute to all elements in the DDL. Only those significant elements that might have an equivalent in the IFC data model have been selected.

Elements in the IFC file that should have a GUID but are not in the list will not be persistent and will vary from export to export.

Command line syntax is available to set/unset the attributes, this calls on the core system to get a system GUID. For example: UUIDENT SET or UUIDENT UNSET.

Note:

If an element already has a set GUID, it cannot be overridden without deliberately unsetting it first. A message is displayed to this effect.

GUID Display Formats

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Inspect the GUIDs

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Additional PML Files

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Set Unset GUIDs

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Check for Duplicate GUIDs

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Collect GUIDs to a File

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Important Information on GUIDs.

Inspect the GUIDs

Internally GUIDs are stored as four integer values on a UUIDIA attribute, these values can be inspected directly using the command.

Uuidia 515327685 300389338 1138094989 250557773

These integers can also be displayed as an IFC GUID window.

IFCUid 0UjqR54UUJsaFLyuqExpLD

This format is useful to allow the coordination between entities in AVEVA E3D™, the IFC file and the source or target package.

Subject to the rule that the value cannot be overridden, if the UUIDIA is already set, the UUIDIA can be reset by hand.

Uuidia 515327685 300389338 1138094989 250557773

Uuidia 515327685 300389338 1138094989 250557774

Uuidia 515327685 300389338 1138094989 250557774

Set the GUID in IFCUID format using text strings.

IFCUid 0UjqR54UUJsaFLyuqExpLD

IFCUid |0000000000000000000000|

IFCUid |0UjqR54UUJsaFLyuqExpLE|

IFCUid 0UjqR54UUJsaFLyuqExpLE

Note:

IFC GUIDs can contain the $ and _ characters. Some sequences of characters (including $) are low level command processor instructions. Without escaping the $ character by doubling it up to $$, there can be unpredictable results.

Any errors invoked during these sequences refer to the underlying UUIDIA attribute.

Note:

Do not set the GUID by hand as it is extremely risky. There is no guarantee that the resultant GUID is unique.

Additional PML Files

Some other PML functions have been written for execution outside the graphical user interface. The functions are necessary if the pure command line is used in batch processes without using the exporter object. The functions are already called from the graphical user interface or exported object.

Note:

If a Savework is not performed before quitting AVEVA E3D™, the GUIDs transferred in the next export will be different.

It is recommended that the functions are run before export as part of working practice for two reasons:

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To make sure that the GUIDs are up to date and that other users can see them.

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To save time during the export process.

Set Unset GUIDs

An PML function, setUnsetGUIDs.pmlfnc, has been written to be called during the export process to detect all unset UUIDIA attributes, and to set them. This can be called from the command line as well in the case of batch processing outside the export graphical user interface.

!!setUnsetGUIDs( !items is ARRAY ) is STRING

!items - an array of DBREF elements

|Unable to set GUID (ref). Is element locked or the database read-only?|

!items = ARRAY()

!items.append( !!ce )

!message = !!setUnsetGUIDs( !items )

write( !message )

Check for Duplicate GUIDs

The interface checks for duplicate UUIDIA attributes during an export process. The function checkDupGuids.pmlfnc performs this function.

!!checkDupGuids( !items is ARRAY, !fixIt is BOOLEAN ) is BOOLEAN

!items - an array of DBREF elements

!fixit - a flag to tell system to replace the duplicate value

|(Warning) - Duplicate GUID found '| + !guid + |' on $!ref and $!prevRef .|

|Cannot set UUIDIA. Is element locked, or database read-only?|

!items = ARRAY()

!items.append( !!ce )

!success = !! checkDupGuids ( !items, true )

Collect GUIDs to a File

The collectGUIDs.pmlfnc function has been written to collect all elements with set UUIDIA attributes and to write a macro that can set them again. This was primarily written for project upgrade, but can provide a template to develop bespoke functionality regarding the UUIDIA attributes.

!!collectGUIDs( !filePath is STRING, !overWrite is BOOLEAN )

!filePath - full path name of output file

!overWrite - flag to overwrite file if it already exists.

!!collectGUIDs( |C:\userPath\userFile.mac|, true )

Important Information on GUIDs

The export process is expected to have write access to the elements being exported. This is because the GUIDs are set where necessary on export.

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