# Datum's: Levels and Grids and Groups

Datum object's are important to any BIM model. This is due in part to the preference of many BIM software's for 'hosted modeling', where object's are modeled in 3D space in relation to a coincident (or nearby) datum object, of which Grids and Level's are the most prevalent. 

When using Konstru, user's should be aware of how the different linked platforms utilize datum objects. These specifics are addressed in depth in the Platform Specific Knowledge sections near the end of this document.

## Grids

The basis for a Konstru database version of a Grid is the base-line that defines the it, and it's Name attribute. 

Grids can be created and updated in almost all of the link Konstru platforms. There are some notable limitations associated with Grids, primarily on the analysis model side:

| Konstru Grid Interoperability                                | SAP | ETABS | RAM | Revit | Tekla |
| ------------------------------------------------------------ | :-: | :---: | :-: | :---: | :---: |
| Users can upload a grid created in this platform to Konstru: |  Y  |   Y   |  Y  |   Y   |   Y   |
| Users can download a Konstru Grid into this platform:        | N\* |  N\*  | Y\* |   Y   |   Y   |

{% hint style="info" %}
SAP - SAP considers 'Grids' as part of a 3D coordinate system which includes 'Levels' also. Whilst Konstru can upload grids created natively in SAP,  this fact limits the ability of Konstru to download new or update existing SAP grids and levels.  
{% endhint %}

{% hint style="info" %}
ETABS Grid Download - Whilst Konstru is unable to create grids in ETABS on download, a work around has been developed that uses a .exe to allow automation of the creation of Konstru grids in ETABS. You can learn more about this tool at the page listed below. You can also leverage a .dxf import of a grid file which some users may prefer of the .exe described below.
{% endhint %}

{% hint style="info" %}
RAM Grid Download - Each individual grid in a Konstru model, when downloaded to a RAM model results in the creation of a RAM Grid System for each independent gird in the Konstru model. 
{% endhint %}

{% content-ref url="/pages/-LK2VyqOyMFxj5kl6Pb2" %}
[Konstru ETABS Grid Importer\*](/konstru-manual/konstru-revit/konstru-etabs/konstru-etabs-grid-importer.md)
{% endcontent-ref %}

## Levels

Level's are an important part of a Konstru model, as they are used by a number of Konstru linked platforms to 'host' objects within the 3D environment. Konstru Level's are defined by their Z elevation, and their Name attribute. 

Whilst the presence of Level's in a Konstru model is not critical, a model downloaded to a number of Konstru platforms the does not include levels will present the user with some issues best avoided. 

### Level Based Platforms - Revit + Tekla + ETABS + RAM

When modeling in the above software, the creation and use of levels is a necessary part of modeling process. Whilst the terminology differs between these software, the general term for this type of approach is called 'hosted modeling'. Any model uploaded to Konstru from one of these platforms will include Level objects. As per the authoring software, any difference between a modeled object and it's host level is recorded as a geometric offset which is captured by Konstru as object attributes. 

### 'Level-less' Platforms - SAP

When modeling in SAP, there is no requirement (or ability to even create!) Level objects. As such a model that is uploaded to Konstru from SAP will not include any Level objects. Konstru is built to address this limitation of SAP with future downloads of this model to platforms which require levels, such as Revit.  


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