timing

type Chain struct {
	Names map[string]string
	Waits map[string][]string
	Loop  []string
}

type Target struct {
	Value    float64
	HasValue bool
	// Month is the month it is due by, or for one set when an event
	// happens the month that is expected by; empty for one that follows
	// an event with no date of its own.
	Month string
	// Pending is a target set when an event happens.
	Pending bool
	Timing  Timing
	// Set is a target defined in any form; Dated is one that says when.
	Set, Dated bool
}

type Timing struct {
	Form string
	// Month is the latest month it can fall in, where it says one: the
	// date, a window's end (else its start), or the month a set-when is
	// expected by. Empty for after an event with no date of its own.
	Month string
	// Event is the event an after or a set-when waits on.
	Event map[string]any
	// Late is a set-when whose expected month has passed.
	Late bool
	// Complete is a timing that says everything its form needs.
	Complete bool
}