diff --git a/tap-version-14-specification.md b/tap-version-14-specification.md
index 5f35a6d..5a5832b 100644
--- a/tap-version-14-specification.md
+++ b/tap-version-14-specification.md
@@ -156,23 +156,31 @@ backwards compatibility.
 
 ### Version
 
-To indicate that this is TAP14 the first line _must_ be
+The TAP version of a TAP stream is indicated on the first line.
 
 ```tap
 TAP version 14
 ```
 
-Harnesses _may_ interpret ostensibly
-[TAP13](https://testanything.org/tap-version-13-specification.html) streams
-as TAP14, as this specification is compatible with observed behavior of
-existing TAP13 consumers and producers.  That is, they _may_ treat this as
-a valid Version line while parsing TAP14:
+If there is no version line on the first line, the TAP version shall be 12.
+
+#### Backwards compatibility of TAP versions
+
+This specification is compatible with observed behavior of existing
+[TAP12](https://testanything.org/tap-specification.html) and
+[TAP13](https://testanything.org/tap-version-13-specification.html) consumers
+and producers.
+
+Harnesses _should_ interpret ostensibly older TAP streams as TAP14.  That is, they
+_should_ treat this as a valid and supported Version line while parsing TAP14:
 
 ```tap
 TAP version 13
 ```
 
-Harnesses _may_ treat any TAP stream lacking a version as a failed test.
+and likewise treat a missing Version line as implicitly TAP14.
+
+Harnesses _may_ instead treat any ostensibly older TAP stream as a failed test.
 
 ### Plan