[R] lpSolve lp const.dir

[Rob Helpert]

Hi.  In the help page for "lp" in package lpSolve, regarding
"const.dir" it says:

const.dir:  Vector of character strings giving the direction of the
constraint: each value should be one of "<," "<=," "=," "==," ">," or
">=". (In each pair the two values are identical.)

I am having trouble understanding the sentence in parenthesis.  What
are the pairs to which the sentence is referring?

More particularly, I am trying to perform linear programming in which
I want to use equality constraints.  That is, I want to implement a
constraint of the form A %*% x = b.  To do so, should I use
   const.dir <- c("==", "==", "==")
or should I use
   const.dir <- c("=", "=", "=")
i.e., should I use strings with one or two equals signs?

Thanks.