Just learning how to rig and when it has come to Extracting Pre-transform, none of the values of seems to change - this is what I have: https://imgur.com/a/lzGV7kR [imgur.com]

Another thing I noticed is that all the values include this ‘-’ (minus) at the end of the value. As a novice i'm not sure what this means. If anyone could assist please..

'Extract Pre-transform' will only extract when there actually is a pre-transform - use the MMB to check the node info.

when you see values like this:
-2.3487545-6
6.34347238-11
etc
these are effectively 0.0
it's a supper tiny value displayed in scientific notation [en.wikipedia.org]
you can just make them 0 manually if they bother you

Thanks goldfarb. Thing is I was following the sidefx tutorial and at this point - http://www.youtube.com/watch?v=cWUHxyjbJ4M&t=15m56s [www.youtube.com] - he links some bones, the values shift, then he ‘Extracts Pre-transforms and his values shift again. Mine essentially didn’t do this and I though id maybe done it wrong - he is using 16.5 and i'm on 17.5, plus I noticed PathCV is slightly different in these 2 versions.

“…he links some bones…” - that would be me

there was a change in Houdini 17.5 and how keep position when parenting operates - before H17.5, the offset would be put into the pre-transform, but in 17.5 the values are put into the local transform, so in this case there is no need to extract the transform.

!!!!! Haha Fab tutorial so far and brill that I'm not in error with this. Thanks so much for helping me out in person

Happy i found this thread! I was wondering about the same things!
I finally got through the tutorial series a few days ago. I was not following along in Houdini but just focusing on the lectures to make sure i understand all.

I wrapped my head around World transform and pre-transform just to start up Houdini 17.5 and see the (newly?) added local transform added in the information of the node. Now the pre-transform stays empty most of the time and values are stored to the local transform.

@Mr. Goldfarb

Could you kindly explain how those changes affect the rigging principles that you taught us?
With world transform and pre transform i understood what was going on, but the newly added local transform kind of puts me back to zero.

It would be great to get a quick high level explanation on what the changes mean for the rigging series.

The series is superb btw! One of the best training out there! Outstanding job!