If you are working on an attribute clean up, either a delete & replace or an attribute manager purge (see attribute management on the BIM manual for which attributes should be managed this way), make sure to back up your attributes first.
Attributes should be backed up by ID, not by name, so that if they do need to be brought back in to fix missing attribute problems, they are reassigned automatically.
To back up your attributes, open the attribute manager under options > element attributes > attribute manager. Select the all tab (upper right), reserve all under the teamwork drop down (bottom left), the select By Index >>. Next select Save As… and save the attributes to a folder in your projects BIM folder on the file server.
When you need to bring an attribute back in, select open in the attribute manager. Opening this AAT file will bring in all attributes. Go to the attribute type you need to restore, find the attribute, select and click << By Index. Note that this will replace an attribute that may have been created or modified to use that original index number, which will change all instances of that attribute’s occurrence in the model.
Also, note that whenever doing an attribute clean up, reserve all first to ensure any replaced attributes are actually replaced in the model elements that use them. Any unreserved elements who’s attributes have been replaced will show as missing attributes.