Add blurb about Schema view

- Add paragraph explaining what the Schema tab is used for and what's displayed in the UI
- Explain that there are 3 tabs - Track, Identify, and Group
- Point out that track events are tracked by the entire event and Identify events are tracked by traits and won't show up unless traits are passed in an identify call
- Mention that "Page Viewed" will be all Page calls and will show up under the Track tab 
- Explain the differences in UI display based on whether a tracking plan is connected or not

Author: sarahrudy

src/connections/sources/schema/index.md

@@ -1,16 +1,25 @@
 ---
-title: Schema Controls
+title: Source Schema 
 redirect_from:
   - '/protocols/schema/'
 ---
 
 {% include content/plan-grid.md name="protocols" %}
 
-
-Segment Business plan customers can use Schema Controls to manage which events are allowed to pass through Segment and on to Destinations. These filters are a first-line defense to help you protect the integrity of your data, and the decisions made with it.
+Segment Business Tier customers can use Schema Controls to manage which events are allowed to pass through Segment and on to Destinations. These filters are a first-line defense to help you protect the integrity of your data, and the decisions made with it.
 
 Blocking events within the source schema will exclude them from API and MTU calculations. These events are discarded before they reach the pipeline that Segment uses for MTU calculations. 
 
+## Schema view
+
+The Schema tab shows the schema of events/properties/traits for each source that Segment receives over a specific timeframe. It also shows when the events were last seen, how many events were allowed vs. blocked, and the downstream destinations those events are connected to.
+
+You can view events by Segment call type in the Source Schema with the **Track**, **Identify**, and **Group** tabs. The Schema tracks Track event details by _event_ name while Identify and Group event details are tracked by _trait_ name. Additional event properties for Page or Track events can be viewed by clicking on the arrow to the left of the event name. Since the Schema tracks **Identify** traits, you will need to make sure you are passing traits into your Identify call in order to view event data in your schema. 
+
+The Schema shows "Page Viewed" for all Page calls under the **Track** tab. 
+
+The Source Schema UI changes slightly depending on whether you have a [Protocols Tracking Plan](https://segment.com/docs/protocols/tracking-plan/create/){:target='_blank’} connected to the source. If you do have a Tracking Plan connected to your source, the UI will show a **Planned** column that will indicate if the event is planned or unplanned. This allows you to quickly identify unplanned events and take action to align your schema with your Tracking Plan. If there is no Tracking Plan connected to the source, the UI will display a toggle next to each event where, if you're a Business Tier customer, you can simply block or allow that event at the source level. More about event filters below. 
+
 ## Event filters
 
 If you no longer want to track a specific event, you can either remove it from your code or, if you're on the Business plan and don't have a Tracking Plan connected, you can block track calls from the Segment UI. To do so, click on the Schema tab in a Source and toggle the event to enable or block an event.
@@ -24,7 +33,7 @@ If you no longer want to track a specific event, you can either remove it from y
 
 Once you block an event, Segment stops forwarding it to all of your Cloud and Device-mode Destinations, including your warehouses. You can remove the events from your code at your leisure. In addition to blocking track calls, Business plan customers can block all Page and Screen calls, as well as Identify traits and Group properties.
 
-When an event is blocked, the name of the event or property is added to your Schema page with a counter to show how many events have been blocked. By default, data from blocked events and properties is not recoverable. You can always re-enable the event to continue sending it to downstream Destinations.
+When an event is blocked, the name of the event or property is added to your Schema page with a counter to show how many events have been blocked. By default, data from blocked events and properties is not recoverable. You can always re-enable the event to continue sending it to downstream Destinations. 
 
 In most cases, blocking an event immediately stops that event from sending to Destinations. In rare cases, it can take **up to six hours** to fully block an event from delivering to all Destinations.
 
@@ -39,6 +48,8 @@ If you no longer want to capture specific traits within `.identify()` and `.grou
 > warning ""
 > Blocked traits are not omitted from calls to device-mode Destinations.
 
+Segment's Page call will be 
+
 ## Schema Integration Filters
 
 All customers can filter specific events from being sent to specific Destinations (except for warehouses) by updating their tracking code. Here is an example showing how to send a single message only to Intercom and Google Analytics:
@@ -62,3 +73,15 @@ Segment Business tier customers can block track calls from delivering to specifi
 
 
 ![Schema integration filters](images/asset_d3SRmkWy.gif "Animation showing how to block events with the toggle switch")
+
+## Schema View
+
+At the top of your source page, you will see a row of tabs. 
+
+The Schema tab shows your Source Schema with all events that flow into that source.
+
+Page calls under the hood are Track calls (with some differences) which is why they can show up under Track calls in some areas of the UI.
+
+The Source Schema view has three 
+
+"Page Viewed" for all Page calls under the Track tab.