Premise: Traverse only supports integer values for polled results (stored 32-bit integer).
As such any metrics (e.g. WMI or SNMP) that are returned as a string will be stored as an arbitrary value (recognized by Traverse) that is mapped to 'Unknown'. An example of an unsupported value within SNMP: when reviewing MIBs, the syntax/type displayed is 'DISPLAYSTRING' (e.g. ifDescr .126.96.36.199.188.8.131.52.1.2).
This information should not be confused with the string display of a test's status displayed in the UI. Many of Traverse's signatures contain value mappings of the reported results that are stored as integers to be displayed as "human readable" (e.g. "Up", "Down", "Testing", and "Normal"). These are generally (if not always) associated with tests that use 'As Test Value Rises, Severity' set to 'Discrete' on the tests' settings page.
Being that the stored value must be an integer it is entirely possible to leverage Traverse's functionality of plugin scripts to map or translate strings to an integer that Traverse can store. Please see the "Plugin Monitors" section of our Traverse Developers Guide for additional information.