Unique rules when forming that grammar are highlighted like this
Example sentences follow these rules too!
Joining and Nesting Markers:
Verb[た/る] - means that dictionary form and ta form are accepted.
Verb[causative[て]] - means て form of the causative form of the verb.
[いかん by itself means "in what way", but it has come to be used similarly to 次第, with expressions of decision making and change like 決める、決まる、決する、決定、予定、(不)可能. However, いかん is less common and more formal]
[いかん can also express a lack of dependency/relation in expressions like いかんによらず、いかんにかかわらず、いかんを問わず]