reader is not passed,
only registering is done. note that already if no register_data
arguments are passed, registration is skipped.
18/06/18 add action argument. Can be  ‘read’, ‘register’ or ‘all’ (default, =read and register). This is useful to give fine control, for example to modify x and y after reading and still make it possible to register data (e.g. this is done in
Data2D.__init__).</p>
</div></blockquote>
</dd></dl>

<dl class="py function">
<dt class="sig sig-object py" id="pySurf.dat