Tuesday, 6 August 2013

Parameters Part 3 - Tags

In part 1, I introduced the various types of parameters and in part 2 I showed how parameters can be filtered to create different graphic views of information which is a very powerful concept.

I part 3, I am going to look at how tags work with parameters. Tags deserve a post in their own right but for now I am going to concentrate on how parameters are used with tags which will be a good introduction to tags.

In Revit, tags are labels or smart text. In many CAD systems, tags are not that smart in the sense that they don't know anything about the object they are related to so it is up to the user to check that all text is up to date prior to issuing a drawing. For example WAL-01 may refer to a standard 126mm plasterboard metal stud partition. WAL-02 includes moisture resistant board to one side for toilets and shower areas. If my layout changes and the shower room is extended, the label for the wall type might not get moved so I am now calling up a standardised partition where I need a moisture resistant version.

The job of coordination is traditionally the architects role but with buildings getting more complex and deadlines and budgets getting increasingly tighter, this kind of coordination is becoming more difficult and mistakes can be costly onsite. The good news is Revit has a solution to this coordination problem as tags are smart enough to know what object they are point to. If you change the wall type, the tag is automatically updated. If you delete the wall, the tag is deleted to as it relies on it completely.

Walls contain built in parameters and parameters just like the shared parameter we created in part 2 for Fire Performance. These parameters can be included in the tags.


Revit includes tags for many families which it calls categories. The tags themselves are families made up of lines and labels. Because each category e.g. Door, Window, Wall, Column, etc has it's own tag, they can be unique. The door tag may contain the Door Number and Fire rating but a Column may contain the diameter or width and height. Revit comes with standard tags for all categories that can be tagged which you can customise for your project or office.

I will add some tags to the sample project I used in part 2. Tags can be added from the Tag panel under the Annotation tab.

Tag by Category allows you to select objects such as walls, doors, etc in the model and will then prompt you to place a tag for that object. Select a wall and a door and you should end up with something like the example below. The tags for doors and walls have different graphics in order to distinguish them.This is how Revit gives you the tags so you can change this if you like. You may want to change how these look to suit industry or office standards. The tags also include data. By default doors contain the Mark and walls contain the Type/Mark. In Revit Mark is a built in parameter which Revit requires to be unique which is very useful for objects such as doors. Type Mark must be unique for each type e.g. No two wall types can have the same Type mark value.

I want to add the Fire Performance for the doors. Remember Fire Performance is a shared instance parameter. I am using this parameter to designate the fire performance required of this door by the Fire Engineer. The fire rating for the door type should meet or exceed this rating which I will evaluate in part 4 of this post by using schedules. In order to include the Fire Performance parameter I need to edit the tag. Select any door tag. You can edit it by either selecting Edit Family from the Modify tab or selecting Edit Family from the context menu available when right clicking the mouse.

You are now in the Family Editor. You can modify the graphics of the label as you wish. These are straightforward lines. The Door Mark value is a label. Labels are smart as they show the parameter value for the object which the label is referring to. Click on the label and then select Edit in the properties window.

Notice Mark is already included under label Parameters. I now want to add Fire Performance which is not yet available under category Parameters. To add it click the new button under category Parameters. Click the Select button and then select the Fire Performance parameter.

Fire Performance will now be available under category parameters. Select it and click the arrow to include it as a new row to the label Parameters. Tick the Break box after Mark. This will create a line break between the mark and Fire Performance value. I have replaced the Sample value with something shorter than Fire Performance. Click OK to complete editing.

The Mark and Fire Performance parameters won't fit inside the bounding lines, so in this case I made the text smaller by creating another label style whose text is 2mm. You could increase the size of the box or what ever is required to make the label readable without being to large to be usable.

You should save the door tag to a project of office specific location for library objects so that it can be reused or edited again. Click Load into Project from the Modify tab to load this tag into the model and replacing the previous version.


The parameters are the i in BiM. Just like Filters in Visibility Graphics for views, tags are a means to convey the information in parameters. Unlike text, Tags are smart as they are associated with one object (or instance) and can convey the instance or type parameters for that object. Any shared parameters that you create can also be included in Tags.

In the future we will get to a point where information is conveyed by use of the model only. For now tags will be a very import means to communicate the scope of a project which it does very quickly and with a significant reduction in the number of coordination errors that can occur in traditional CAD systems.

The updated sample model is available here.

1 comment:

  1. Is it possible to make a parameter like "mark" to identify sections of conduit with a unique tag? to don´t repeat the tag.

    not using the default tag, i want to create a new with the same properties to avoid to repeat the consecutive number and to identify the differents section of conduits by trades.