Clarification on grid and obstacle tags in map configuration

[sheviarivas]

Hello! What's the correct use of tags obstacles and grid? I've read the README file, but there are things that I don't quite understand

1. About the tag grid: if a cell is marked by a number different than 0, the expected behaviour would be that an agent can never be in that cell?

2. About the tag obstacle: can agents go through obstacles?

3. It's there a functional difference between marking a cell as untraversable cell, and defining a square-shaped obstacle that occupies the same cell?

4. Also, if a cell is marked as untraversable, should it have obstacles surround it? for example:

   <map>
        <width>2</width>
        <height>2</height>
        <cellsize>1</cellsize>
        <grid>
            <row>0 0</row>
            <row>1 1</row>
        </grid>
  </map>

Should the obstacles look like this?

  <obstacles number="1" >
        <obstacle>
            <vertex xr="0" yr="0"/>
            <vertex xr="2" yr="0"/>
            <vertex xr="2" yr="1"/>
            <vertex xr="0" yr="1"/>
        </obstacle>
  </obstacles>

5. For the previous map configuration, is this setup valid this too?

  <obstacles number="2" >
        <obstacle>
            <vertex xr="0" yr="0"/>
            <vertex xr="1" yr="0"/>
            <vertex xr="1" yr="1"/>
            <vertex xr="1" yr="0"/>
        </obstacle>
        <obstacle>
            <vertex xr="1" yr="0"/>
            <vertex xr="2" yr="0"/>
            <vertex xr="2" yr="1"/>
            <vertex xr="1" yr="1"/>
        </obstacle>
  </obstacles>

Thank you very much for your time. Best regards