ridewithgps provides the following download file types:

1) gpx track -> most accurate representation of the path. This is many gps coordinate points close together.
2) gpx route -> the gps coordinates for the just turns (waypoints) and cue-sheet directions as labels for each point (direction to turn and street name).
3) txc -> Garmin specific format. It's an extension of the gpx format (it's basically a combination of 1 and 2).
4) cue-sheet -> text cue sheet instructions (like what you'd print out as a cue-sheet).
5) kml -> Google earth specific file containing the track (equivalent to 1, I believe).

I suspect that the cue-sheet app uses 2 (you can open this file in a text editor and it will make some sense to you).

ridewithgps does alot of work to set up the file so that it's easy to use in an app like cue-sheet.

Here's an example of the sort of information 2 contains:

The numbers are the gps coordinates.
"name" is the direction to display for the arrow.
"cmt" is the spoken/displayed direction to take.

<rtept lat="34.82518" lon="-89.99475000000001">
<name>Generic</name>
<cmt>Start of route</cmt>
</rtept>

<rtept lat="34.82781" lon="-89.9948">
<name>Left</name>
<cmt>Turn left onto W Robinson St</cmt>
</rtept>

<rtept lat="34.82786" lon="-89.99751000000003">
<name>Right</name>
<cmt>Turn right onto Timber Ln</cmt>
</rtept>

<rtept lat="34.83026" lon="-89.99966">
<name>Right</name>
<cmt>Turn right onto Ludlow Dr</cmt>
</rtept>

<rtept lat="34.83185" lon="-89.99711000000002">
<name>Right</name>
<cmt>Turn right onto Northwood Hills Dr</cmt>
</rtept>

<rtept lat="34.8317" lon="-89.99479000000002">
<name>Left</name>
<cmt>Turn left onto US-51 N</cmt>
</rtept>

<rtept lat="34.83349" lon="-89.99471">
<name>Left</name>
<cmt>Slight left onto Memphis St</cmt>
</rtept>