</dd>


<dt>pos_sep</dt>
<dd><p>a character string indicating the character that connects the
core label and the position, (e.g., "_" for "X_1", "Y_1", ...).</p></dd>


<dt>pos_ids</dt>
<dd><p>the vector of IDs used for indexing the x-coordinates,
y-coordinates etc. (e.g., 1:101 for time-normalized trajectories from
MouseTracker). If unspecified (the default), column labels for the
respective variable will be extracted using grep (see Details).</p></dd>


<dt>reset_timestamps</dt>
<dd><p>logical indicating 