[Discuss-gnuradio] GRC Building Block Internals

[John B. Wood]

Hello, everyone, and I trust most of you will indulge a GRC newbie.  
After reading some of the online Gnuradio docs, I'm puzzled by what's 
inside building blocks that appear in the GRC block tree panel.  If I 
select "WBFM Receive" from the "Modulators" tab, for example, I know 
this defined by the analog_wfm_rcv.xml file in my 
/usr/local/share/gnuradio/grc/blocks directory.  When I examine this 672 
byte file with a text editor, the what entries are there make sense but 
how can this block define an entire FM receiver (Filters, FM detector, 
etc) from I & Q signal inputs to baseband audio?  It doesn't seem 
possible.  What am I overlooking?

The other question is whether any of these building blocks were 
themselves created using GRC signal flow graphs and how to display them 
as such.  Thanks for your time and comment.  Sincerely,