descriptions

In the conference call on Monday night, the main AMS
committee (specifically Martin O'Leary) decided that
using an attribute for descriptions did not actually
help compatibility with V-2001, since I insisted that
the attribute for params, variables, and nets (ports)
be after the item.

Putting the attribute before the item, to comply with
V-2001's use of attributes, is ugly:
  (*desc="Forward Early voltage"*) parameter real vef = 44.0 from (0.01:inf);
  (*desc="Fraction of the emitter-base depletion capacitance that belongs to the sidewall"*) parameter real XCJE = 0.4 from [0.0:1.0];

compared with
  parameter real VEF = 44.0 from (0.01:inf) --- "Forward Early voltage";
  parameter real XCJE = 0.4 from [0.0:1.0] --- "Fraction of the emitter-base depletion capacitance that belongs to the sidewall";

I see three remaining issues:

1) Module descriptions: it seems to me that we could use
the attribute for this; having it on the line above the
module declaration makes it function as a nice comment
in the code:
  (*desc="Mextram 504 Bipolar transistor model"*)
  module bjt504(c,b,e,s);

2) Since V-2001 doesn't have disciplines, putting the port
description on the discipline declaration line means that
you can't describe a digital port.

On the other hand, if you put the description on the
input/output/inout declaration, then you can't describe
the internal nodes of semiconductor devices.

Presumably, we don't want two ways to attach a description.

3) For net/port descriptions, we had allowed a description
to apply to multiple net_identifiers:
  electrical (*desc="input"*) in1, in2, (*desc="output"*) out;

I don't think this is possible with the --- syntax; do we care?
You'd have to do
  electrical in1 --- "input", in2 --- "input", out --- "output";

which is still an improvement over V-2001, which would have to do:
  (*desc="input"*) input in1, in2;
  (*desc="output"*) output out;

-Geoffrey
Received on Wed May 26 07:05:05 2004