When dealing with GIS source code you often need to write latitude and longitude coordinate tuples.

E.g. in Google Maps links (123, 456):

<http://maps.google.com/maps/ms?msid=214518704716144912556.00046d7689a99e95b721c&msa=0&ll=123,456&spn=0.007996,0.026865>

Which is preferred order (and why?)

* latitude, longitude
* longitude, latitude

I have seen both being used in various systems and I hope to find some evidence to stick with other one.

Is there a standard practice, and if so, what is it / what are they?