diff --git a/docs/fundamentals/archive-nodes.md b/docs/fundamentals/archive-nodes.md
index df593475a..d39d81172 100644
--- a/docs/fundamentals/archive-nodes.md
+++ b/docs/fundamentals/archive-nodes.md
@@ -13,8 +13,9 @@ Two independent groups of configuration options compose:
 ## Archive shapes
 
 - **Full archive** answers every historical query at every height, state and receipts, from genesis.
-- **Windowed archive** answers everything a full archive does, but only for the last [`FlatDb.HistoryRetentionBlocks`](./configuration.md#flatdb-historyretentionblocks) blocks. Older queries are refused with a pruned-history error - never answered wrongly from live state. Disk stays bounded: the pruner reclaims continuously as the window rolls.
+- **Windowed archive** answers everything a full archive does, but only for the last [`FlatDb.HistoryRetentionBlocks`](./configuration.md#flatdb-historyretentionblocks) blocks, with [`FlatDb.HistoryRetention`](./configuration.md#flatdb-historyretention) set to `Rolling`. Older queries are refused with a pruned-history error - never answered wrongly from live state. Disk stays bounded: the pruner reclaims continuously as the window rolls.
 - **Address-slice archive** is a windowed node whose named contracts additionally answer to their full slice depth - state, logs, and transactions - while everything else rolls with the window.
+- **Since-block archive** keeps everything from a fixed block onward, forever: set [`FlatDb.HistoryRetention`](./configuration.md#flatdb-historyretention) to `SinceBlock` and [`FlatDb.HistoryRetentionSinceBlock`](./configuration.md#flatdb-historyretentionsinceblock) to that block. Nothing below it is captured and queries there fail closed; nothing above it is ever pruned. For blocks and receipts from the same point, use `History.Pruning=UseAncientBarriers` with the ancient barriers set to that block; see [History pruning](./history-pruning.md). Slices (`FlatDb.HistorySliceAddresses`) keep their block-and-receipt retention in this mode; their flat-history side has nothing to keep, since nothing is ever pruned. This suits operators whose indexers only need history from a known starting point that never moves.
 
 ## Configuration
 
@@ -24,7 +25,9 @@ Each option is documented in its own section of the [configuration reference](./
 |---|---|---|---|---|
 | [`FlatDb.Enabled`](./configuration.md#flatdb-enabled) | `true` | `true` | `true` | The flat database itself. |
 | [`FlatDb.HistoryEnabled`](./configuration.md#flatdb-historyenabled) | `true` | `true` | `true` | Captures the per-block state changesets. |
-| [`FlatDb.HistoryRetentionBlocks`](./configuration.md#flatdb-historyretentionblocks) | `0` (default) | the window size, in blocks | the window size, in blocks | The state-history window; `0` keeps state history from genesis. |
+| [`FlatDb.HistoryRetention`](./configuration.md#flatdb-historyretention) | `None` (default) | `Rolling` | `Rolling` | Whether flat history is kept unbounded, in a rolling window, or from a fixed block onward (`SinceBlock`, see below). |
+| [`FlatDb.HistoryRetentionBlocks`](./configuration.md#flatdb-historyretentionblocks) | - | the window size, in blocks | the window size, in blocks | Size of the rolling window. Required with `Rolling`, rejected otherwise. |
+| [`FlatDb.HistoryRetentionSinceBlock`](./configuration.md#flatdb-historyretentionsinceblock) | - | - | - | First block to keep. Required with `SinceBlock`, rejected otherwise. |
 | [`FlatDb.HistorySliceAddresses`](./configuration.md#flatdb-historysliceaddresses) | unset | unset | the sliced addresses | Contracts kept queryable beyond the general window. |
 | [`History.Pruning`](./configuration.md#history-pruning) | `Disabled` (default) | `Rolling` | `Rolling` | Block-and-receipt expiry; see [History pruning](./history-pruning.md). |
 | [`History.RetentionEpochs`](./configuration.md#history-retentionepochs) | - | the retention window, in epochs | the retention window, in epochs | How much block-and-receipt history the rolling pruner keeps. |
@@ -36,7 +39,7 @@ Each option is documented in its own section of the [configuration reference](./
 Every archive setting is default-off: a node that configures none of them behaves exactly as before.
 
 :::warning Important
-Setting `FlatDb.HistoryRetentionBlocks` to a non-zero value selects the windowed row format and requires fresh flat history: enabling it on an existing unwindowed flat-history database is refused, and there is no in-place conversion. Start with a fresh sync.
+`FlatDb.HistoryRetention=Rolling` or `SinceBlock` selects the windowed row format and requires fresh flat history: enabling it on an existing unwindowed flat-history database is refused, and there is no in-place conversion. Start with a fresh sync.
 :::
 
 :::warning Important