Expressions are a fundamental concept within Jira Workflow Toolbox: every input into the JWT expression editor is considered an expression and will be interpreted by the JWT expression parser against the selected parsing mode.
Expressions range from simple text, e.g.
Hello world!, over mathematical calculation, e.g.
3 + 4, to the extensive usage of expression parser functions, and beyond.
Basic text mode being the simplest one among the parsing modes allows to write free text and insert field codes. The other parsing modes support the usage of operators and expression parser functions.