--- a/doc/Modem-configs	Thu Aug 03 05:20:46 2017 +0000
+++ b/doc/Modem-configs	Thu Aug 03 16:49:35 2017 +0000
@@ -30,11 +30,18 @@
 		be built for all targets, and it is currently the most deblobbed
 		(closest to full source) Magnetite config.
 
-All 3 of the above configurations have CSD, fax and GPRS enabled, i.e., include
-functionality that will only become exercisable when we build our FCDEV3B and
-is dead weight until then, while we limp along with the currently available
-hardware.  Having deblobbed all of L1 except GPRS-specific modules, we are now
-in a position where we can build a hybrid config with GPRS excluded, optionally
+All 3 of the above configurations have CSD, fax and GPRS enabled; this
+functionality can only be exercised on those hardware targets on which both
+Calypso UARTs are brought out, with the MODEM UART presenting a standard ASCII
+AT command interface including data functions, while the IrDA UART carries the
+RVTMUX interface for debug trace and other development functions.  If you are
+interacting with your Calypso target modem or pseudo-modem solely through
+RVTMUX, without access to the ASCII AT command interface on the dedicated MODEM
+UART, then the data functions of the firmware are inaccessible and act as dead
+weight.
+
+Having deblobbed all of L1 except GPRS-specific modules, we are now in a
+position where we can build a hybrid config with GPRS excluded, optionally
 including or excluding FAX_AND_DATA, but I (Mychaela) would like to thoroughly
 exercise the hybrid config in its current everything-enabled state before making
 further changes to it.
@@ -56,6 +63,4 @@
 applied to our Citrine fw, hence the latter now has working voice calls too.)
 However, it is almost certain that there are a ton of minor bugs which need to
 be shaken out, hence this firmware build config should be treated as
-experimental for the time being, not production.  My plan is to work on shaking
-out the minor bugs and bringing this hybrid fw to production quality after we
-build the proper hardware platform for it, i.e., the FCDEV3B.
+experimental for the time being, not production.