In a column, you can merge adjacent cells, but the argument used is different depending on if you are working in a table or grid. Below is one example for each. 

Tables in Report

autoMerge="True" controls automatic merge of adjacent cells in a column with the same object.

Configuration

<Report>
<Table autoMerge="True">
    <Columns>
        <ItemNameColumn width="200" objectName="SoftwareComponents" caption="Software Component"/> 
        <ItemNameColumn width="200" objectName="Signals" caption="Signal"/>
    </Columns> 
    
    <!--List all Software Components-->
    <ForEach select="/ARSC">  
        <RowObject name="SoftwareComponents">
            <!--List all Signals (Receive ports)-->  
            <ForEach select="/ARRP"> 
                <RowObject name="Signals">
                    <Row/>
                </RowObject> 
            </ForEach> 
        </RowObject>
    </ForEach>
</Table>
</Report>

Result

Grids

cellMerge="True" defines if adjacent cells with identical values in the column should be merged into a single cell. Possible values "True" and "False" (default).

Configuration

<Grid>
  <Columns>
    <ItemNameColumn width="200" objectName="SoftwareComponents" cellMerge="True" caption="Software Component"/> 
    <ItemNameColumn width="200" objectName="Signals" caption="Signal"/>
  </Columns> 
    
    <!--List all Software Components-->
  <ForEach select="/ARSC">  
    <RowObject name="SoftwareComponents">
      <!--List all Signals (Receive ports)-->  
      <ForEach select="/ARRP"> 
        <RowObject name="Signals">
          <Row/>
        </RowObject> 
      </ForEach> 
    </RowObject>
  </ForEach>
</Grid>

Result