add function namespaces

Author: tfitzmac

articles/azure-resource-manager/bicep/bicep-functions.md

@@ -2,7 +2,7 @@
 title: Bicep functions
 description: Describes the functions to use in a Bicep file to retrieve values, work with strings and numerics, and retrieve deployment information.
 ms.topic: conceptual
-ms.date: 09/09/2021
+ms.date: 09/30/2021
 ---
 
 # Bicep functions
@@ -11,13 +11,28 @@ This article describes all the functions you can use in a Bicep file. For a desc
 
 Most functions work the same when deployed to a resource group, subscription, management group, or tenant. A few functions can't be used in all scopes. They're noted in the lists below.
 
+## Namespaces for functions
+
+All Bicep functions are contained within two namespaces - `az` and `sys`. Typically, you don't need to specify the namespace when you use the function. You specify the namespace only when the function name is the same as another item you've defined in the Bicep file. For example, if you create a parameter named `range`, you need to differentiate the `range` function by adding the `sys` namespace.
+
+```bicep
+// Parameter contains the same name as a function
+param range int
+
+// Must use sys namespace to call the function. 
+// The second use of range refers to the parameter.
+output result array = sys.range(1, range)
+```
+
+The `az` namespace contains functions that are specific to an Azure deployment. The `sys` namespace contains functions that are used to construct values. The `sys` namespace also includes decorators for parameters and resource loops. The namespaces are noted in this article.
+
 ## Any function
 
-The [any function](./bicep-functions-any.md) is available in Bicep to help resolve issues around data type warnings.
+The [any function](./bicep-functions-any.md) is available in Bicep to help resolve issues around data type warnings. This function is in the `sys` namespace.
 
 ## Array functions
 
-The following functions are available for working with arrays.
+The following functions are available for working with arrays. All of these functions are in the `sys` namespace.
 
 * [array](./bicep-functions-array.md#array)
 * [concat](./bicep-functions-array.md#concat)
@@ -36,42 +51,42 @@ The following functions are available for working with arrays.
 
 ## Date functions
 
-The following functions are available for working with dates.
+The following functions are available for working with dates. All of these functions are in the `sys` namespace.
 
 * [dateTimeAdd](./bicep-functions-date.md#datetimeadd)
 * [utcNow](./bicep-functions-date.md#utcnow)
 
 ## Deployment value functions
 
-The following functions are available for getting values related to the deployment:
+The following functions are available for getting values related to the deployment. All of these functions are in the `az` namespace.
 
 * [deployment](./bicep-functions-deployment.md#deployment)
 * [environment](./bicep-functions-deployment.md#environment)
 
 ## File functions
 
-The following functions are available for loading the content from external files into your Bicep file.
+The following functions are available for loading the content from external files into your Bicep file. All of these functions are in the `sys` namespace.
 
 * [loadFileAsBase64](bicep-functions-files.md#loadfileasbase64)
 * [loadTextContent](bicep-functions-files.md#loadtextcontent)
 
 ## Logical functions
 
-The following function is available for working with logical conditions:
+The following function is available for working with logical conditions. This function is in the `sys` namespace.
 
 * [bool](./bicep-functions-logical.md#bool)
 
 ## Numeric functions
 
-The following functions are available for working with integers:
+The following functions are available for working with integers. All of these functions are in the `sys` namespace.
 
 * [int](./bicep-functions-numeric.md#int)
 * [min](./bicep-functions-numeric.md#min)
 * [max](./bicep-functions-numeric.md#max)
 
 ## Object functions
 
-The following functions are available for working with objects.
+The following functions are available for working with objects. All of these functions are in the `sys` namespace.
 
 * [contains](./bicep-functions-object.md#contains)
 * [empty](./bicep-functions-object.md#empty)
@@ -82,7 +97,7 @@ The following functions are available for working with objects.
 
 ## Resource functions
 
-The following functions are available for getting resource values:
+The following functions are available for getting resource values. Most of these functions are in the `az` namespace. The list functions and the getSecret function are called directly on the resource type, so they don't have a namespace qualifier.
 
 * [extensionResourceId](./bicep-functions-resource.md#extensionresourceid)
 * [getSecret](./bicep-functions-resource.md#getsecret)
@@ -99,7 +114,7 @@ The following functions are available for getting resource values:
 
 ## Scope functions
 
-The following functions are available for getting scope values.
+The following functions are available for getting scope values. All of these functions are in the `az` namespace.
 
 * [managementGroup](./bicep-functions-scope.md#managementgroup)
 * [resourceGroup](./bicep-functions-scope.md#resourcegroup) - can only be used in deployments to a resource group.
@@ -108,7 +123,7 @@ The following functions are available for getting scope values.
 
 ## String functions
 
-Bicep provides the following functions for working with strings:
+Bicep provides the following functions for working with strings. All of these functions are in the `sys` namespace.
 
 * [base64](./bicep-functions-string.md#base64)
 * [base64ToJson](./bicep-functions-string.md#base64tojson)