G64 P and Q

Is G64 P0.001
the same as
G64 P0.001 Q0.00 ?
and Q0.00 is the same as no Q ?
I think the documentation suggests this but it's not stated explicitly.
I haven't been using Q, mostly because I don't fully understand what is default.

You may not use Q complitly, type only G64 P0.001 and it will work

P0.001 was a poor example for this question.
Something from 5 years back:

"Ok, I was helped to understand this better and it is not a bug. P does set the motion tolerance and Q sets Naive Cam Detector tolerance, but if Q is not specified it defaults to the same setting you give P. I fixed my problem by specifying Q0 or even Q0.001"

sourceforge.net/p/emc/bugs/426/
So unless things have changed this is the answer

In your example is shown how param. P is work.
As for me I've never used Q.
As I understand Q makes borders in two sides of path that tool can't move out.
So if you want to make pricese move simply use G61. And if not G64 Pn.
You can try if G64 P1 Q0 will be equal to G61

Thanks aleksamc
I think the light is starting to shine.

No, Q has to do with line segment collinearity. If two consecutive segments are less than Q from being collinear (in other words in a straight line) they are merged and treated as a single line segment. (Q is expressed in degrees). If Q is not specified it is set as Q=P. If you want to use Q value of 0 you must specify it explicitly such as G64P0.01Q0. Q can be important to speed up the running of some poorly generated g-code made by some CAM systems by preventing unnecessary slow downs.

I was wondering if in the absence of a reasonable Q value, it would be pretty easy
to run out of the default TP lookahead with gcode consisting of many tiny G1 moves.

Todd wrote:

If Q is not specified it is set as Q=P.

Revisiting the g-code overview docs this is stated clearly. I ended up on the trajectory planner page and got lost in the wilderness. For now I've programmed some small segment arcs and back plotting in Axis in an attempt to grasp the rest. If it doesn't sink in I'll stick with P only which has done okay so far.

I did a little testing, and I'm not sure that you can always trust what the backplot shows with regards to this.

Yes, the back plotting doesn't match the documentation. Most likely Axis was never intended for this kind of thing so it shouldn't be a surprise. Filed under "if all you have is a hammer".