diff --git a/docs/assembler/masm/proto.md b/docs/assembler/masm/proto.md
index 4d6df6754c..25491dc441 100644
--- a/docs/assembler/masm/proto.md
+++ b/docs/assembler/masm/proto.md
@@ -1,7 +1,7 @@
 ---
 title: "PROTO | Microsoft Docs"
 ms.custom: ""
-ms.date: "08/30/2018"
+ms.date: "10/22/2018"
 ms.technology: ["cpp-masm"]
 ms.topic: "reference"
 f1_keywords: ["PROTO"]
@@ -14,12 +14,44 @@ ms.workload: ["cplusplus"]
 ---
 # PROTO
 
-Prototypes a function.
+Prototypes a function or procedure. You can call the function prototyped by the PROTO directive by using the [INVOKE](https://docs.microsoft.com/en-us/cpp/assembler/masm/invoke?view=vs-2017) directive.
 
 ## Syntax
 
-> *label* PROTO [[*distance*]] [[*langtype*]] [[, [[*parameter*]]:*tag*]]...
+> *label* **PROTO** \[*distance*] \[*langtype*] \[__,__ \[*parameter*]__:__*tag*] ...
+
+### Parameters
+
+*label*<br/>
+The name of the prototyped function.
+
+*distance*<br/>
+(Optional) Used in 16-bit memory models to override the default and indicate **NEAR** or **FAR** calls.
+
+*langtype*<br/>
+(Optional) Sets the calling and naming convention for procedures and public symbols. Supported conventions are:
+
+- 32-bit **FLAT** model: **C**, **STDCALL**
+
+- 16-bit models: **C**, **BASIC**, **FORTRAN**, **PASCAL**, **SYSCALL**, **STDCALL**
+
+*parameter*<br/>
+The optional name for a function parameter.
+
+*tag*<br/>
+The type of a function parameter.
+
+The *parameter* and *tag* parameters may appear multiple times, once for each passed argument.
+
+## Example
+
+This sample shows a **PROTO** declaration for a function named `addup3` that uses a **NEAR** call to override the 16-bit model default for procedure calls, and uses the **C** calling convention for stack parameters and return values. It takes two arguments, a **WORD** and a **VARARG**.
+
+```MASM
+addup3 PROTO NEAR C, argcount:WORD, arg1:VARARG
+```
 
 ## See also
 
-[Directives Reference](../../assembler/masm/directives-reference.md)<br/>
\ No newline at end of file
+[Directives Reference](directives-reference.md)<br/>
+[.MODEL Reference](dot-model.md)<br/>