Reading documentation about BIM un Maximo, there is only COBie mentioned.

Then I found this IBM Ideas, it is marked as Impelemented.

It there really full IFC support in Maximo/MAS?

Hello Juris.  Let me take a minute and explain the Maximo BIM Integration, there are 2 parts.
1 - BIM Project - which provides an ability to import "as-built" engineering data into Maximo and register assets/locations and supporting reference data such as classification, specification, person, Items, Job plans, documents, etc.  This capability leverages the COBie file format.
2 - BIM Viewer - this is a separate plugin which can be installed in MAS or EAM that is a connection to Autodesk.  The plugin allows user to upload a 3D model file and make it viewable in Maximo.  The plugin supports many file formats include ifc.  Typical formats might be rvt, dwg, nwd or others.  The plugin will upload the 3D model into the cloud and translate it to a format that is readable in Maximo 3D tab. 

All that said, we have released an update in MAS Civil 9.1 that will convert the asset data in an ifc into a loadable Maximo format.  The user can select to create a COBie file or a Maximo Data Loader file that can then be loading either using BIM Projects or Maximo Data Loader.  

Reading documentation about BIM un Maximo, there is only COBie mentioned.

Then I found this IBM Ideas, it is marked as Impelemented.

It there really full IFC support in Maximo/MAS?