Intent

Retain conjunctions that join clauses together.

Motivation

Conjunctions can be categorized as coordinate, subordinate, or correlative. The coordinate conjunctions connect elements of equal rank – words, phrases, clauses. The subordinate conjunctions connect dependent elements to independent ones. The correlative conjunctions are used in pairs – one complementing the other. The following table provides a representative sample of the various kinds of conjunctions.

category	subcategory	examples
coordinate	additive	also, and, besides, both, likewise, moreover, then
	adversative	but, however, nevertheless, notwithstanding, still, yet
	disjunctive	but, either, else, or, neither, nor, other, otherwise
	final	consequently, for, hence, so, thus, therefore
subordinate	reason	as, because, for, hence, inasmuch, since, whereas, wherefore
	degree	as, else, other, otherwise, rather, than
	concession	although, provided, nevertheless, save, though
	condition	if, provided, since, unless
	manner	as, how
	place	after, before, whence, whereat, wherever
	purpose	lest, that, so that
	time	as, before, ere, since, still, till, until, when, whenever
correlative	both-and	both boys and girls are going.
	either-or	either boys or girls will go.
	neither-nor	neither boys nor girls will go.
	if-then	if you fail, then must try again.

Applicability

Use joined clauses when

• you’ve simplified some statements with isolated verb, but
• you discover that some clauses only make sense when paired together.

Considerations

Many independent clauses describe conditions or situations that can occur in the world (and thus in a problem domain). Situations, conditions, and constraints are generally testable and verifiable. These kinds of statements hold special significance throughout software development, from requirements through code, because they usually describe some qualities that need to be established and maintained (enforced). Thus, the primary object responsibility categories include ensuring quality.

Many complete nuclear sentences stand on their own (as independent clauses), but some statements only make sense in relation to others, especially when one of them (a dependent clause) describes a possible situation, a condition, or a constraint.

While simple sentences can stand alone, you can also compose them to describe situations.

a building stores type 1 hazardous chemicals and
that building also stores type 2 hazardous chemicals

While comparative relations can stand alone, you can also compose them to describe conditions or constraints.

a building’s drum storage count equals its drum storage limit and
a neighboring building’s drum storage count equals its drum storage limit

Consequences

You can use a condition description to simplify some conditions. The previous condition can be simplified as follows:

a full storage building = a storage building whose drum count equals its drum storage limit
a full storage building neighbors another full storage building

You can pair clauses to produce a condition – action pair that describes a behavior rule or a business rule. Consider the following example of a condition – action pair:

the EPA closes a chemical storage facility if …
the chemical storage facility violates a safety regulation

You can use a clause summary to simplify some rules. Consider the following simplification of the foregoing rule.

storage facility closure = the EPA closes a chemical storage facility
safety violation = a chemical storage facility violates a safety regulation

a safety violation triggers a storage facility closure

Some correlative conjunctions are coordinate and some are subordinate. Thus, you can treat them as described above based on their usage.