Add draft spec

Author: baileympearson

source/client-side-operations-timeout/client-side-operations-timeout.md

@@ -427,6 +427,16 @@ check the command document for the presence of a `maxTimeMS` field.
 
 See [runCommand behavior](#runcommand-behavior).
 
+### Explain Helpers
+
+If a driver provides an explain helper, drivers MUST take care to ensure that timeoutMS is correctly applied to the top-level
+explain command, when specified.  Care should be taken by drivers with a fluent API - the following example
+should apply a timeoutMS of 1000 to the `explain` command:
+
+```typescript
+collection.find({}, { timeoutMS: 1000 }).explain();
+```
+
 ## Test Plan
 
 See the [README.rst](tests/README.md) in the tests directory.

source/crud/crud.md

@@ -2198,6 +2198,24 @@ the [$readPreference global command argument](../message/OP_MSG.md#global-comman
 [passing read preference to mongos and load balancers](../server-selection/server-selection.md#passing-read-preference-to-mongos-and-load-balancers)
 (if applicable).
 
+
+### Explain
+
+Some drivers provide explain helpers.  If a driver does provide explain helpers, the driver MUST ensure that its helper permits users to
+specify options for the explain command specifically.  An example, using Node, might look like:
+
+```typescript
+collection.find({ name: 'john doe' }).explain({ maxTimeMS: 1000 });
+
+// sends:
+{ 
+  explain: { find: <collection>, query: { name: 'john doe' } },
+  maxTimeMS: 1000
+}
+```
+
+Drivers MUST document how users can specify options on their explain helpers.
+
 ## Test Plan
 
 See the [README](tests/README.md) for tests.

source/crud/tests/README.md

@@ -676,3 +676,14 @@ InsertOne {
 
 Execute `bulkWrite` on `client` with `model`. Assert that an error (referred to as `error`) is returned. Assert that
 `error` is a client error containing the message: "bulkWrite does not currently support automatic encryption".
+
+### 14. `explain` helpers allow users to specify `maxTimeMS`
+
+Create a MongoClient with command monitoring enabled (referred to as `client`).
+
+Create a collection, referred to as `collection`, with the namespace `explain-test.collection`.
+
+Run an explained find on `collection`.  The find will have the query predicate `{ name: 'john doe' }`.  Specify
+a maxTimeMS value of 2000ms for the `explain`.
+
+Obtain the command started event for the explain.  Confirm that the top-level explain command should has a `maxTimeMS` value of `2000`.