Help with definitions: I keep confusing where the zero value lies for the apsis compared to where it lies for the ordnance.

[frctl]

I keep confusing where the zero value lies for the apsis compared to where it lies for the ordnance. I have drawn a picture demonstrating below:



Is someone able to help me by defining either definitions so that I know which is present on a particular plane or during my math questions.

 

[stapel]

I keep confusing where the zero value lies for the apsis compared to where it lies for the ordnance. I have drawn a picture demonstrating below:

View attachment 36210

Is someone able to help me by defining either definitions so that I know which is present on a particular plane or during my math questions.

Does "apsis" mean "abscissa"? Does "ordnance" mean "ordinate"?

If you are referring to the definitions of abscissa and ordinate, they are just the input (usually [imath]x[/imath]) and the output (usually [imath]y[/imath]), respectively.

What do you mean by "which is present on a particular plane or during my math questions"?