diff --git a/libc/docs/headers/assert.rst b/libc/docs/headers/assert.rst
new file mode 100644
index 000000000000000..06ea27966de1ae1
--- /dev/null
+++ b/libc/docs/headers/assert.rst
@@ -0,0 +1,27 @@
+.. include:: ../check.rst
+
+========
+assert.h
+========
+
+Macros
+======
+
+.. list-table::
+  :widths: auto
+  :align: center
+  :header-rows: 1
+
+  * - Macro
+    - Implemented
+    - C23 Standard Section
+    - POSIX.1-2024 Standard Section
+  * - __STDC_VERSION_ASSERT_H__
+    - |check|
+    - 7.2.1
+    -
+  * - assert
+    -
+    - 7.2.1
+    -
+
diff --git a/libc/docs/headers/errno.rst b/libc/docs/headers/errno.rst
new file mode 100644
index 000000000000000..f25aae4f23b2c70
--- /dev/null
+++ b/libc/docs/headers/errno.rst
@@ -0,0 +1,35 @@
+.. include:: ../check.rst
+
+=======
+errno.h
+=======
+
+Macros
+======
+
+.. list-table::
+  :widths: auto
+  :align: center
+  :header-rows: 1
+
+  * - Macro
+    - Implemented
+    - C23 Standard Section
+    - POSIX.1-2024 Standard Section
+  * - EDOM
+    -
+    - 7.5
+    -
+  * - EILSEQ
+    -
+    - 7.5
+    -
+  * - ERANGE
+    -
+    - 7.5
+    -
+  * - errno
+    -
+    - 7.5
+    -
+
diff --git a/libc/docs/headers/index.rst b/libc/docs/headers/index.rst
index 2a7bf59e0b56dbe..7a9186a7c66e864 100644
--- a/libc/docs/headers/index.rst
+++ b/libc/docs/headers/index.rst
@@ -4,9 +4,12 @@ Implementation Status
 .. toctree::
    :maxdepth: 1
 
+   assert
    complex
    ctype
+   errno
    fenv
+   locale
    math/index.rst
    search
    setjmp
diff --git a/libc/docs/headers/locale.rst b/libc/docs/headers/locale.rst
new file mode 100644
index 000000000000000..2d5525bd3f2f9ad
--- /dev/null
+++ b/libc/docs/headers/locale.rst
@@ -0,0 +1,63 @@
+.. include:: ../check.rst
+
+========
+locale.h
+========
+
+Macros
+======
+
+.. list-table::
+  :widths: auto
+  :align: center
+  :header-rows: 1
+
+  * - Macro
+    - Implemented
+    - C23 Standard Section
+    - POSIX.1-2024 Standard Section
+  * - LC_ALL
+    - |check|
+    - 7.11
+    -
+  * - LC_COLLATE
+    - |check|
+    - 7.11
+    -
+  * - LC_CTYPE
+    - |check|
+    - 7.11
+    -
+  * - LC_MONETARY
+    - |check|
+    - 7.11
+    -
+  * - LC_NUMERIC
+    - |check|
+    - 7.11
+    -
+  * - LC_TIME
+    - |check|
+    - 7.11
+    -
+
+Functions
+=========
+
+.. list-table::
+  :widths: auto
+  :align: center
+  :header-rows: 1
+
+  * - Function
+    - Implemented
+    - C23 Standard Section
+    - POSIX.1-2024 Standard Section
+  * - localeconv
+    - |check|
+    - 7.11.2.1
+    -
+  * - setlocale
+    - |check|
+    - 7.11.1.1
+    -
diff --git a/libc/utils/docgen/assert.json b/libc/utils/docgen/assert.json
new file mode 100644
index 000000000000000..28ec12028ef6758
--- /dev/null
+++ b/libc/utils/docgen/assert.json
@@ -0,0 +1,10 @@
+{
+  "macros": {
+    "__STDC_VERSION_ASSERT_H__": {
+      "c-definition": "7.2.1"
+    },
+    "assert": {
+      "c-definition": "7.2.1"
+    }
+  }
+}
diff --git a/libc/utils/docgen/errno.json b/libc/utils/docgen/errno.json
new file mode 100644
index 000000000000000..aface8e42b495f5
--- /dev/null
+++ b/libc/utils/docgen/errno.json
@@ -0,0 +1,16 @@
+{
+  "macros": {
+    "EDOM": {
+      "c-definition": "7.5"
+    },
+    "EILSEQ": {
+      "c-definition": "7.5"
+    },
+    "ERANGE": {
+      "c-definition": "7.5"
+    },
+    "errno": {
+      "c-definition": "7.5"
+    }
+  }
+}
diff --git a/libc/utils/docgen/locale.json b/libc/utils/docgen/locale.json
new file mode 100644
index 000000000000000..89329f9aae5b0f6
--- /dev/null
+++ b/libc/utils/docgen/locale.json
@@ -0,0 +1,30 @@
+{
+  "macros": {
+    "LC_ALL": {
+      "c-definition": "7.11"
+    },
+    "LC_COLLATE": {
+      "c-definition": "7.11"
+    },
+    "LC_CTYPE": {
+      "c-definition": "7.11"
+    },
+    "LC_MONETARY": {
+      "c-definition": "7.11"
+    },
+    "LC_NUMERIC": {
+      "c-definition": "7.11"
+    },
+    "LC_TIME": {
+      "c-definition": "7.11"
+    }
+  },
+  "functions": {
+    "setlocale": {
+      "c-definition": "7.11.1.1"
+    },
+    "localeconv": {
+      "c-definition": "7.11.2.1"
+    }
+  }
+}