Definition

A characteristic of a named transition that's typical — present in most instances by default; absent cases are diagnostic but don't exclude the instance from the category.

Position in the three-tier sort

Condition tiering sorts the candidate characteristics of a transition into three tiers — Essential, Expected, and Related — by their definitional role. Expected is the middle tier: more frequent than Related, less binding than Essential.

Essential characteristics are definitional. Drop one, and the instance falls outside the named transition. Related characteristics are correlated and plausibly present, but they don't determine whether an instance belongs. Expected sits between — present in most instances by default, with absent cases staying inside the category.

The discrimination work differs across tiers. Essential characteristics cleanly separate named transitions from non-instances. Expected characteristics give probabilistic signal. Related characteristics are weakly indicative. The only structural distinction between Expected and Related is frequency — how often the characteristic appears across instances — and that distinction governs nothing downstream. Expected and Related feed the same operations once the sort is done.

Absence as signal

An absent Expected characteristic doesn't disqualify the instance. The instance still meets the Essential characteristics, so it's still inside the category. What's changed is that the instance has departed from the typical case, and that departure carries information about this particular instance — its situation, its conditions, what made it deviate from the default pattern.

Use in auxiliary routes

Expected characteristics, alongside Related characteristics, feed auxiliary routes — user activity that's structurally in scope for the parent transition but not causally required for its critical route. Auxiliary routes are where the team designs around the broader terrain users predictably traverse, not just the minimum the critical route names.

A path designed only against Essential characteristics will support the strict minimum and miss the activity users routinely bring with them. Expected characteristics name the predictable parts of that broader terrain.

Example

For an invoicing tool's "first invoice sent" transition, the Essential characteristics are roughly: invoice created with line items, recipient specified, send action successfully fired. A logo on the invoice is Expected — most users upload one before sending their first invoice, but the invoice still counts as sent without one. A sole proprietor invoicing from a personal email may never upload a logo at all.

Treating the logo as Essential would shrink the transition's population to exclude valid first-invoice users. Treating it as incidental would miss that logo-upload friction is a common drag on the broader path. Putting it in the Expected tier surfaces the design implication: build affordances for the logo-upload auxiliary route, but don't treat logo upload as a gate on the signup cohort's first paid conversion.

See also

• Completion criteria — the Essential tier made operational; what Expected characteristics are explicitly not part of
• Affordance landscape — the broader terrain Expected characteristics help map
• Path — the slice of the landscape the provider shapes deliberately; what auxiliary routes get designed into