Let's trace the TCXOEN signal from the Calypso.  Calypso ball A12, no trace
visible, guessing a micro-via right under the ball.  L1 coord (3739,1053).
Guess appears right: on L2 there is a connection from a micro-via to an inner
via, the latter is at (3712,1055).  Found it on L4: the via is in the middle of
a trace going both ways!  Right branch goes to (4548,1028); left branch goes to
(1699,1349).

Following the branch at (4548,1028): found it on L2, microvia back to L1 at
(4518,1048).  Found it on L1, goes to some 2-pad footprint, can't tell if it's
unpopulated or a faint black resistor.  The other end goes to a via at
(4676,919).  Found it on L2, goes to inner via at (5135,684).  Found it on L7,
goes to surface via at (5132,716).  Found it on L8 - goes to flash reset input
on ball D5.  (Previously erroneously reported as RY/BY# ball E5.)

Following the branch at (1699,1349): found it on L2, immediately goes back to
L1 at (1673,1353).  Found it on L1, go to UL pad of the VCTCXO, passing by a
cap to GND.  The cap is populated.

Let's trace the signal from the VCTCXO to the Rita.  VCTCXO pin is unknown, but
the input to Rita corresponds to a surface via at (2161,488) - at this point on
L1 there is an unpopulated cap(?) to GND and a series component (cap?) to the
actual Rita input.  Found it on L2, goes back to L1 at (2123,1284).  On L1 it
falls right into the UR pad of the VCTCXO!  Conclusion: the signal from VCTCXO
to Rita passes through a single series component, just like in Rita datasheet.

The LR pad of the VCTCXO is GND.  Thus the control input must be the LL pad.
The input signal to here passes first through a series component, then passes
by a comp to ground, and then goes into the VCTCXO input.  The entry point to
the whole arrangement is a surface via at (1669,1488).  Found it on L2, inner
via at (1655,1467).  Found it on L4, goes to (2932,855).  Found it on L2,
surface via to L1 at (2950,837).  That's Iota ball J4 (AFC), and there is also
a branch from there that goes to an unpopulated cap(?) footprint to GND.