The parameter is the exact text that appears between the square brackets.
soft
indirect
{like this}
The parameter is the text indicated by the text reference whose name appears between the curly brackets, i.e. a field of a specified tiddler, or the value of a property of a specified data tiddler.
variable
<like this>
The parameter is the current value of the variable whose name appears between the angle brackets. Macro parameters are not supported.
New in: 5.1.23 Filter operators support multiple parameters which are separated by a , character.
For example: [param1],[param2] or <param1>,{param2}