Why is RBuf is not called HBuf though allocated on heap ?

Hi ,

While trying to find the answer to my question-"If RBuf is something like a modifiable descriptor which is allocated on heap or someting like HBuf, why it is called RBuf ?" - I came across following lines from a document from Symbian Ltd.

1)RBuf descriptors can live on the stack, but maintain a pointer to memory in the heap. On the stack, they take up 8 bytes more than an HBufC* (i.e. 3 words rather than 1), but will generally take up 4 bytes less heap space (if not constructed from an existing BufC).
2)
The new descriptor is not named HBuf because, unlike HBufC, objects of this type are not themselves directly created on the heap (the H prefix stands for heap); choosing an R name carries the implication that the class owns the resources (in this case a Buf) that it manages and is responsible for freeing the memory when it closes.

Now, will somebody help me understand what "On the stack, they take up 8 bytes more than an HBufC* (i.e. 3 words rather than 1), but will generally take up 4 bytes less heap space (if not constructed from an existing BufC) means in a simple manner."

Next, will you tell me what "not themselves directly created on the heap" means and how they are allocated.

Thanks and Regards,
--NN