# How to organize labels when there are too many equations?

I'm writing a moderately long text using LaTeX, and it's great to be able to organize chapters, sections, appendices, and everything else almost automatically. One thing has been bothering me though. This text has a lot of equations (multi or single-lined), and I can't find a convenient way to handle the labels.

Since the text is still being written, I can't tell whether I'll need to reference a given equation later on, so I'm just labeling all of then. What I'd like though, is for latex to only number the equations that are cited somewhere in the text. I'm using the align environment (since most equations are multi-line). After researching a bit, I've found the following options:

1. Use the align* environment instead, and manually \tag the equations. This is not very convenient, since the tagging is done manually as well as the citing. Also, I'm constantly going back and adding equations, which would force me to change every tag that comes after the added equation in that section (not as bad as I thought at first).

2. Keep using align and \label, but \notag each line, and then remove the \notag once I realize I want to cite that equation. This is the best I could find, but it is still cumbersome. Emacs automatically adds the labels, but not the notags.

Is this really it? LaTeX always manages to surprise me in how there's a package for everything. Isn't there one that hides the labels unless it's been called by an \eqref?

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"Also, I'm constantly going back and adding equations, which would force me to change every single tag that comes after the added equation." No it wouldn't. It would only mean this if you are just labelling equations with a number, which is a really bad idea, and only partly for the reason that they need renumbering if you add anything. – Seamus Sep 16 '10 at 16:10
@Seamus: Correct, I'm editing the question. – Bruce Connor Sep 16 '10 at 16:26
If the \notag macro (and the split environment) really aren't enough, then manually labelling-and-tagging the equations you do refer to seems like the best option to me. But then, I'm also patient enough to 'manually' \label any equation to which I refer. – Niel de Beaudrap Sep 16 '10 at 17:33
I just found out about the split environment. Seems promising. – Bruce Connor Sep 17 '10 at 18:21