From c6462286a0ce6d0cb0adeace22dc58f54436a260 Mon Sep 17 00:00:00 2001
From: Dan Dascalescu <ddascalescu+github@gmail.com>
Date: Mon, 26 Sep 2016 15:51:54 -0700
Subject: [PATCH] Briefly explain how to split element definition

---
 PRIMER.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/PRIMER.md b/PRIMER.md
index 11b77286e0..2acf35791e 100644
--- a/PRIMER.md
+++ b/PRIMER.md
@@ -467,7 +467,8 @@ Example:
 We say that an element definition has an imperative and declarative portion. The imperative
 portion is the call to `Polymer({...})`, and the declarative portion is the `<dom-module>`
 element. The imperative and declarative portions of an element's definition may be placed
-in the same html file or in separate files.
+in the same HTML file or in separate files. They are matched mased on the `id` and `is`
+properties having the same value.
 
 **NOTE:** Defining an element in the main html document is not currently supported.