Question about True Position (Cartesian Tolerance)

Hello,

Will someone please give me an "Explain Like I'm 5" explanation of this -

"To measure the true position of the holes to the wall, a .435” gauge pin needs to be inserted into one of the holes (Datum EL per sheet 10 on drawing). Take a .158” pin (.158” is the nominal distance from the wall to the hole) and slide it in between the wall and the .435” pin. With a .010” true position, it allows for a +/-.0035” Cartesian tolerance. Depending on the fit of the .158” pin, go bigger or smaller in gauge pin size to measure the correct dimension."

I am having a hard time with this for some reason. Maybe it's worded weirdly, or I'm just tired. Either way any assistance is appreciated.

Thank you,
-G

First, where does this question come from? Who's training material?

It is not from any training material. It is instructions on how to measure a feature on a part/print and I am just having a hard time interpreting the instructions. Specifically in regards to how to produce the requested measurements using the tools that I'm being instructed to use. I am helping an inspector at work with this, and thought maybe you folks could help.....because I'm stuck. Another engineer produced these instructions but he isn't here. Please let me know if you require any additional information.

Here's what I think it says...


[LIST=1][*]Find/identify the feature identified as Datum EL on sheet 10. Should be the letters “EL” contained within a box with a leader attached to a surface or similar.[*]Get a gauge pin of diameter .435 and insert into one of the identified holes.[*]Using a tall enough precision angle push the surface identified as Datum EL against it and hold in firmly in place.[*]Get a pin of .158 precision length and place between the precision angle and the .435 pin.[*]If there is a gap get a longer pin to close the distance between the precision angle and the .435 diameter pin.[*]The final pin length should be .158 +/- .0035 in length.[/LIST]