Microstation Cell Library

are you unfamiliar with mstn terminology? Are you more familiar with Acad?

Acad > Blocks > microstation cells > made of multiple models within  a    Name.cell file

Acad > Xref > microstation  external reference file but can be nested ie  an xref that has other xrefs attached ie nested..

Now a cell that has been built ( in a model) in a name.cel file  can have other cells attached within the same cell model this is called a nested cell but this should be discouraged as they are prone to break or fail  better to copy all the data into one cell and drop it  so its not a cell anymore inside another cell..

Another  extremely bad practice prone to go wrong is a cell with Xrefs attached..

If the source data unwittingly is moved deleted or edited this can have profound problems when you try to place your cell .. this was mentioned already but it made sense to cover all bases in this post, your again better off to merge the xref into the cell model and the cell then is independent of the xref...but displays what you want... if you want traceability then  in your xref put a non printable level text to tell users if you change this then update the cell name and name.cel file  and in the cell description list that it comes from xref name etc.

You cant really automate everything and still let other use common data unless everyone understands where and what things are used for .. again documentation and education need to be foremost if you want standards and automation in a common workspace...

Jan/Lorys,

Thanks for all the help.  I finally got it.  Microstation has evolved a lot since 1986!  I was not aware of this "Referencing" in cells.

Dilip Bhandarkar

One thing to remember is Microstation and AutoCad handle cells differently. The shared cell concept Autodesk uses has never worked well in Microstation (yet).

I am a firm believer in using the software any way you like to your advantage, but I highly recommend never using a reference in a cell.

Bob,

Thanks. I never used reference in a cell.  In fact, I didn't even know that I could do that.  The cell libraries I am dealing with were created starting in 1986 and had nested cells. Remember at that time one couldn't create levels and there were no tags, so to put some intelligence in a cell the nested cell was one option.

Dilip Bhandarkar

Bob,

Thanks. I never used reference in a cell.  In fact, I didn't even know that I could do that.  The cell libraries I am dealing with were created starting in 1986 and had nested cells. Remember at that time one couldn't create levels and there were no tags, so to put some intelligence in a cell the nested cell was one option.

Dilip Bhandarkar

Dilip Bhandarkar said:

I never used reference in a cell.

But you or somebody else obviously did ;-)

Dilip Bhandarkar said:

In fact, I didn't even know that I could do that.

This feature came with MicroStation V8 nearly 20 years ago. Before V8, the cell library used special format, but it was removed in V8, when normal DGN V8 format has started to be used for cell libraries too.

Dilip Bhandarkar said:

The cell libraries I am dealing with were created starting in 1986 and had nested cells.

In such case they it had to be different cell library, not the original one.

The cell definition, created using nested cells, cannot magically change to flat cell and attached references. Somebody has to do create such structure manually.

Dilip Bhandarkar said:

Remember at that time one couldn't create levels

Yes, before V8 DGN format, DGN V7 supported only fixed 63 numbered levels (with description optionally).

Dilip Bhandarkar said:

and there were no tags

Tags were introduced in MicroStation 95, but frankly, I do not remember whether they were supported by cell libraries at this time too ;-)

Dilip Bhandarkar said:

so to put some intelligence in a cell the nested cell was one option.

The nested cells were used often and widely, both by MicroStation itself and 3rd party applications. It makes sense, especially because there were no other (simple enough and widely supported) ways. E.g. SmartSolids are deeply nested cells with a lot of attributes attached, also e.g. OpenBuilding Designer use cells to group elements into objects.

Today, from more reasons, Bentley prefer other data structures. For example parametric cells, even when named "cells", have no relation to cells at all, but are stored as internally linked (dependency relationships) elements, interpreted by MicroStation as one consistent object.

Regards,

  Jan