Update SQL export doc

Author: LTA-Thinking

articles/healthcare-apis/fhir/export-data.md

@@ -32,7 +32,7 @@ The FHIR service supports `$export` at the following levels:
 * [Group of patients](https://hl7.org/Fhir/uv/bulkdata/export/index.html#endpoint---group-of-patients)\*: `GET {{fhirurl}}/Group/[ID]/$export`  
     \*The FHIR service exports all referenced resources but doesn't export the characteristics of the group resource itself.
 
-Data is exported in multiple files. Each file contains resources of only one type. The number of resources in an individual files will not exceed 50,000 and is chosen based on system performance. The result is that you might get multiple files for a resource type, and they'll be enumerated (for example, `Patient-<number assigned by FHIR service>-1.ndjson`, `Patient-<number assigned by FHIR service>-2.ndjson`).
+Data is exported in multiple files. Each file contains resources of only one type. The number of resources in an individual file will be limited. The maximum number of resources is based on system performance. It is currently set to 50,000, but can change. The result is that you might get multiple files for a resource type. The file names will follow the format `<resourceName>-<number>-<number>.ndjson`. The order of the files is not guarentied to corispond to any ordering of the resources in the database.
 
 > [!Note] 
 > `Patient/$export` and `Group/[ID]/$export` can export duplicate resources if a resource is in multiple groups or in a compartment of more than one resource.
@@ -65,7 +65,7 @@ The FHIR service supports the following query parameters for filtering exported
 | `_type` | Yes | Allows you to specify which types of resources will be included. For example, `_type=Patient` would return only patient resources.|
 | `_typeFilter` | Yes | To request finer-grained filtering, you can use `_typeFilter` along with the `_type` parameter. The value of the `_typeFilter` parameter is a comma-separated list of FHIR queries that further limit the results. |
 | `_container` | No |  Specifies the name of the container in the configured storage account where the data should be exported. If a container is specified, the data will be exported into a folder in that container. If the container isn't specified, the data will be exported to a new container with an autogenerated name. |
-| `_till` | No |  Allows you to export resources that have been modified till the specified time. This parameter is applicable only with System-Level export |
+| `_till` | No |  Allows you to export resources that have been modified till the specified time. This parameter is applicable only with System-Level export. In this case, if historical versions exist, export guarantees true snapshot view, or, in other words, enables time travel. |
 
 > [!Note]
 > Only storage accounts in the same subscription as the FHIR service are allowed to be registered as the destination for `$export` operations.