...
The process for accessing data baseline metrics is very similar to the general process for using the Data Access Layer (DAL); documentation can be found here. So, to retrieve data from metrics in the proposed, signed, and approved baselines, you will use the key with 'p', 's', and 'a', respectively.
Method 1:
At the end of your DAL request, simply add the parameter: '&baseline=<key>', where key is any of 'p', 's', and 'a'.
Method 2:
Just as one specifies metrics when using the DAL, you simply prefix the desired metric with an indicator and specify metrics in the same manner. So So, to retrieve data from metrics in the proposed, signed, and approved baselines, you prefix each metric with 'p_', 's_', and 'a_', respectively.
...
You might also want to check out these related topics: