This doesn't work as it should:
type= getParam( 'type', 'e', 'electric or magnetic', { 'values':['e','m'], 'labels': ['Ey wrt B', 'Bz wrt B'] } )
The GUI should have the type='e' or type='m' in the URI, but it includes the label part:
.../Ey_or_Bz_wrt_B.jyds?timerange=2018-04-01+9:11+to+9:23&type='e: Ey wrt B'
I've made it so that string types where the default does not contain a colon will trim this after the colon. This is klugey though and the metadata could keep track of the added labels, or the "view" part of the droplist could add the labels.