---
title: "KeepLadderInput"
description: "a ladder to keep: its ordered rungs, each a predicate over the population that is kept by its hash in the same call, and the rung that qualifies"
section: concepts
address: /concepts/keepladderinput
contract: 0476e35e6e275db5
---

# KeepLadderInput

a ladder to keep: its ordered rungs, each a predicate over the population that is kept by its hash in the same call, and the rung that qualifies

[figure: KeepLadderInput is a value at none scope. The drawing shows its fields and the objects that they point at.]

| property | value |
|---|---|
| kind | value |
| scope | none |
| key | none |
| store | none |
| family | harness |



## Fields


| field | type | required | note |
|---|---|---|---|
| `ladder` | [Ladder](/concepts/ladder) | yes | the rungs carry their predicates by hash; a rung whose predicate is given in full under `predicates` is kept first |
| `predicates` | [Predicate](/concepts/predicate) | no | the rungs' predicates in full, kept by their hashes before the ladder |



## Routes that use it
- [`/v1/act/keep_ladder`](/reference/act/keep_ladder) takes it as input