guideline

Associate names with blocks when they are nested.

Trip:
   declare
      ...
   begin  -- Trip
      Arrive_At_Airport:
         declare
            ...
         begin  -- Arrive_At_Airport
            Rent_Car;
            Claim_Baggage;
            Reserve_Hotel;
            ...
         end Arrive_At_Airport;
      Visit_Customer:
         declare
            ...
         begin  -- Visit_Customer
            -- again a set of activities...
            ...
         end Visit_Customer;
      Departure_Preparation:
         declare
            ...
         begin  -- Departure_Preparation
            Return_Car;
            Check_Baggage;
            Wait_For_Flight;
            ...
         end Departure_Preparation;
      Board_Return_Flight;
   end Trip;

rationale

When there is a nested block structure, it can be difficult to determine which end corresponds to which block. Naming blocks alleviates this confusion. The choice of a good name for the block documents its purpose, reducing the need for explanatory comments. If a name for the block is very difficult to choose, this could indicate a need for more thought about the algorithm.

This guideline is also useful if nested blocks are broken over a screen or page boundary.

It can be difficult to think up a name for each block; therefore, the guideline specifies nested blocks. The benefits in readability and second thought outweigh the inconvenience of naming the blocks.