diff --git a/code/features-index/index-forward/readme.md b/code/features-index/index-forward/readme.md
index 22b4ed96..545fbf1e 100644
--- a/code/features-index/index-forward/readme.md
+++ b/code/features-index/index-forward/readme.md
@@ -1,7 +1,19 @@
 # Forward Index
 
-The forward index contains a mapping from document id to word id. It also provides document-level
-metadata, and a document-to-domain mapping. 
+The forward index contains a mapping from document id to various forms of document metadata.  
+
+In practice, the forward index consists of two files, an `id` file and a `data` file.
+
+The `id` file contains a list of sorted document ids, and the `data` file contains 
+metadata for each document id, in the same order as the `id` file, with a fixed
+size record containing data associated with each document id.
+
+Each record contains a binary encoded [DocumentMetadata](../../common/model/src/main/java/nu/marginalia/model/idx/DocumentMetadata.java) object,
+as well as a [HtmlFeatures](../../common/model/src/main/java/nu/marginalia/model/crawl/HtmlFeature.java) bitmask.
+
+Unlike the reverse index, the forward index is not split into two tiers, and the data is in the same
+order as it is in the source data, and the cardinality of the document IDs is assumed to fit in memory,
+so it's relatively easy to construct.
 
 ## Central Classes
 
diff --git a/code/features-index/index-forward/src/main/java/nu/marginalia/index/forward/ForwardIndexReader.java b/code/features-index/index-forward/src/main/java/nu/marginalia/index/forward/ForwardIndexReader.java
index 04e4fce1..5d26de82 100644
--- a/code/features-index/index-forward/src/main/java/nu/marginalia/index/forward/ForwardIndexReader.java
+++ b/code/features-index/index-forward/src/main/java/nu/marginalia/index/forward/ForwardIndexReader.java
@@ -20,8 +20,8 @@ import static nu.marginalia.index.forward.ForwardIndexParameters.*;
  * and a mapping between document identifiers to the index into the
  * data array.
  * <p/>
- * Since the total data is relatively small, this is attempted to be
- * kept in memory to reduce the amount of disk thrashing.
+ * Since the total data is relatively small, this is kept in memory to
+ * reduce the amount of disk thrashing.
  * <p/>
  * The metadata is a binary encoding of {@see nu.marginalia.idx.DocumentMetadata}
  */
diff --git a/third-party/openzim/readme.md b/third-party/openzim/readme.md
index ee47e601..df9af456 100644
--- a/third-party/openzim/readme.md
+++ b/third-party/openzim/readme.md
@@ -1,11 +1,7 @@
 # OpenZIM
 
-[OpenZIM](https://github.com/openzim/libzim) - GPL-2.0
+[OpenZIM](https://github.com/openzim/libzim) - GPL-2.0+
 
 OpenZIM is a ZIM file reader. This code has been modified in a fairly crude manner 
 to be much faster than the original code base which seems quite antique. It also 
 supports XZ compression.
-
-**Important Note** the license is incompatible with AGPL 3, so we can't link Marginalia 
-directly to this. It's still very useful for building tools that deal with 
-wikipedia data which would be stand-alone.  
\ No newline at end of file