The MIDI standard states that a CC68 controller with a value of 127 would make a series of notes played with the attack phase omitted thus achieving a true legato.  This does not seem to work with Sonar X3 Producer instruments.  Is there a way this can be achieved?  This is very important to me especially for phrasing of woodwinds, brass and solo strings.
 

... a true legato.  This does not seem to work with Sonar X3 Producer instruments.  Is there a way this can be achieved?

 
That was an update to the original MIDI spec as an attempt to standardize legato implementation.  I haven't seen this widely adopted in synthesizers.  In Rapture, you can force a Polyphony of 0 with MIDI Learn of a CC68.  I don't believe you can do the same in Dimension Pro.
 
But you may be able to fake it in DimPro with Sample Offset in the MIDI Matrix, or you can construct it with .sfz scripting.  I can't think of an 'automatic' method in the standard Cakewalk synths that doesn't involve setting it up yourself.

I think I got caught up on "attack phase omitted," so I may not be on the same page with you. As clarification, the "attack phase" to me is the time between sound off to sound on. Rapid attacks are percussive, and slow attacks "swell" gradually. I am assuming you are referring to the swell of legato.
 
As far as Producer instruments. Dimension Pro may be the easiest to achieve this with, as you can graphically manipulate the attack to your taste easily. On the user interface you can click and drag the envelope points without programming any MIDI. I would recommend inserting Dimension Pro into a new project as a simple instrument track and see if that is what you are looking for. (DimPro can have 4 elements included as well, so can tailor sounds in this way.)
 
If I missed the mark in understanding/answering your question please let us know... there are some awesome folks in here that know MIDI far better than I.
 
Welcome to the forum and Happy Holidays!

Thanks for the replies.  Mettelus, I will try this later this evening and see how it goes.  It really will change things for me if I can get it to work. It sounds promising.
Musically its like the difference between a flute player blowing steady and changing the notes as opposed to tonging each note in a series of sixteenth notes. Having that attack on each note when you don't want it is just ugly.
 
b rock,  good to know that it was a later addition to the standard.  I have found some indication on The Net that other numbers may work the same way.  Inexact science.  Sheesh...

For those (like me) who aren't very familiar with all these controller switches, here is a good chart:
http://nickfever.com/402/...esources/midi-cc-list/

If you're looking for global control over attack in Dimension or Rapture, you can use CC 73 (with CC 72 for global release time).  These control the 'master' envelope over all of the individual Elements.  As such, you won't get any faster attacks or longer release times than the individual amplitude envelopes themselves (or whatever may be 'locked' into the samples being played).
 
But CC 73 can be used dynamically - in conjunction with playing technique - to resemble true legato.  A Polyphony setting of 1 will be monophonic with retriggered attacks.  A Polyphony of 0 is the mono-legato setting.  Two or more held notes continue the initial envelope without additional attack phases.
 
A little goes a long way when you're using the global attack / release controls.  Values of 0-31 or 0-15 might be more useful than the full range of 0-127 in CC 73 or CC 72.  It's going to depend on the samples used, AMP EG settings at the Element level, etc.

b rock,
Awesome, it sounds close to what I am looking for.