problems with methods trees
Some aspects of methods trees present barriers to authors and to readabiity.
1. methodStep is required, even though the author may be describing sampling (a sibling to methodStep). The requirement could be altered by changing the model from a sequence to a sequence followed by choice. Some backward incompatibility might occur.
2. In general, methodStep was intended to be human-readable and mimic some degree of natural language (rather than to be machine-parsable). However some methods elements are not organized intuitively.
3. instrumentation: some limitations of the instrumentation tree have been observed. sensorML is now available (http://www.opengeospatial.org/standards/sensorml) and should be considered in any enhancements in this area.