P,Q,R notation in Vector Fields

[says]

Homework Statement

Vector field is given by:
[PLAIN]http://tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsVectorFields_files/eq0001M.gif[PLAIN]http://tutorial.math.lamar.edu/Classes/CalcIII/LineIntegralsVectorFields_files/empty.gif [Broken]
I'm just reviewing line integrals of vector fields and I was wondering what P, Q and R represent?

Homework Equations

The Attempt at a Solution

 

[jedishrfu]

P,Q,R are scalar functions that depend on the position x,y,z.

http://tutorial.math.lamar.edu/Classes/CalcIII/VectorFields.aspx