BinaryEncoding.md: Add nw_iti custom section

1 files changed, 18 insertions, 0 deletions

diff --git a/BinaryEncoding.md b/BinaryEncoding.md
index 2f23e89..135b98f 100644
--- a/BinaryEncoding.md
+++ b/BinaryEncoding.md
@@ -564,6 +564,24 @@ in-memory.
 | ----- | ---- | ----------- |
 | index | uint32* | Type index, as expressed by the [function section](#function-section), encoded as little-endian
 
+### NanoWasm import type index section
+
+Custom name `name` field: `"nw_iti"`
+
+The NanoWasm import type index section is a
+[custom section](#high-level-structure). It is therefore encoded with id `0`
+followed by the name string `"nw_iti"`. It is meant as a
+[NanoWasm](#NanoWasm.md) extension to the MVP that allows NanoWasm-compatible
+interpreters to quickly retrieve the offset where the
+[`external_kind`](#import-entry) (and, optionally, its `type`) members of
+an import entry are located, in order to avoid reading unneded information
+from the [import section](#import-section) or keep this information
+in-memory.
+
+| Field | Type | Description |
+| ----- | ---- | ----------- |
+| offset | uint32* | Offset inside the [import section](#import-section), encoded as little-endian |
+
 ### NanoWasm function body offset section
 
 Custom section `name` field: `"nw_fbo"`