When a company is ‘dead’ the last available closing price is repeated when you use the Datatype P. When you choose P#T this will not happen.
This is taken from the definition in Datastream Navigator:
For this padded datatype the #T qualifier unpads values after the series goes dead – so displays N/A rather than pad the last real value. The series will still be padded where the closing price is not published by an exchange for a stock due to:
The stock does not trade
The stock is suspended
An exchange holiday
This #T applies to more datatypes, for example MV#T (market value) and PI#T (price index).