MicroStation - Grouping Part 2 - Unnamed (Orphan) Cells

In MicroStation - Grouping Part 1 I mentioned ‘Orphan Cells’, and strongly discouraged their use.

To recap, the simplest grouping method in MicroStation is selecting a set of elements then pressing Ctrl + G. Groups created this way are unnamed or ‘Orphan Cells’ that have many of the attributes of cells but none of the control or management tools. Excessive numbers of ‘Orphan Cells’ can eventually lead to file irregularities. 'Ctrl + G' is a V7 concept!

When you want to make a change to the group, then the group has to be dropped using Ctrl + U. Once the changes are made re-select and press Ctrl + G to re-group. This is fine in a simple example but if the group is complex and amongst many other elements re-grouping can be time consuming.

Whilst quick initially, the effects downstream can become very dirty.

Recent cases involving groups have included large groups of vast extent that have compromised IFC export processes. Dropping the unnamed cell (and if necessary re-grouping by other means) has resolved such problems. One source of such groups can be very large blocks brought in from DWG where entire floor models or similar large assemblies (that would be reference files in MicroStation) are converted to unnamed cells.

We offer some functionality to help handle and mitigate the confusion that can be created by widespread use of unnamed cells.

The most obvious is that in Element Information an unnamed cell can be given a name, note the empty space highlighted in red where the name should be, a name canbe entered in the cell name property highlighted in green:

This helps to keep track of what the cell is for or may contain.

A word of warning! This method can also be used to rename instances of library cells. Don't do this as the name is used by the Replace Cell tool, if the cell name is changed the tool cannot search for the original by name.

Unnamed cells are listed in Project Explorer under the File tab, expand the active models:

Note the tree of three unnamed cells. Once they are named you at least know what they represent:

Once a cell has been named one immediate aspect of it's behaviour changes, the Ctrl + U key-in no longer works to ungroup, the Drop Element > Complex tool must be used to ungroup.

There is no quick one click option to add newly named cells to a cell library. The quickest route is probably to drop them and follow the usual cell creation workflow.

Just to reiterate, the advice above is given to assist in a context where unnamed calls have been created from existing data or uninformed processes, I strongly recommend that other grouping methods are used as discussed in MicroStation - Grouping Part 1.

  • Hi Duncan,

    I was either mistaken when I said that the Replace Cell tool can be used to replace a newly named cell with a library cell or this ability existed in earlier versions and has been removed. I found a post in an archived forum suggesting that there are performance reasons for making orphan cells apart from library cells. I have removed the relevant paragraph from this blog.

    Thank you for pointing this out.

  • Hi Marc, 

    Have been following this workflow, however I am finding that after I have given the orphan cell a name, I am unable to replace the cells. 

    Gives me the following error when I try-  'Unnamed or Orphan cells are not supported by this tool. So even after naming the cells, they are still not recognised as 'cells' 

    Additionally, in CE, the explorer does not show groups under file resources. Only shared cells are shown here.