Couple of changes for better alignment between the specs + list forma…

…tting

best-practices.md

@@ -470,11 +470,11 @@ if you follow these recommendations.
 4. Sub-Catalogs or sub-Collections should be stored in subdirectories of their parent
    (and only 1 subdirectory deeper than a document's parent, e.g. `.../sample/sub1/catalog.json`).
 5. Items should be stored in subdirectories of their parent Catalog or Collection. 
-This means that each Item and its assets are contained in a unique subdirectory.
+   This means that each Item and its assets are contained in a unique subdirectory.
 6. Limit the number of Items in a Catalog or Collection, grouping / partitioning as relevant to the dataset.
 7. Use structural elements (Catalog and Collection) consistently across each 'level' of your hierarchy.
    For example, if levels 2 and 4 of the hierarchy only contain Collections, 
-don't add a Catalog at levels 2 and 4.
+   don't add a Catalog at levels 2 and 4.
 
 #### Dynamic Catalog Layout
 

catalog-spec/catalog-spec.md

@@ -36,8 +36,9 @@ and fields to be compliant.
 This Catalog specification primarily defines a structure for information to be discoverable. Any use 
 that is publishing a set of related spatiotemporal assets is strongly recommended to also use the 
 STAC Collection specification to provide additional information about the set of Items 
-contained in a Catalog, in order to give contextual information to aid in discovery. Every STAC Collection contains all
-the same fields as Catalog, though returns 'Collection' instead of 'Catalog' for the type field.
+contained in a Catalog, in order to give contextual information to aid in discovery.
+STAC Collections all have the same fields as STAC Catalogs, but with different allowed 
+values for `type` and `stac_extensions`.
 
 ## Catalog fields
 
@@ -89,8 +90,8 @@ The following types are commonly used as `rel` types in the Link Object of a STA
 | ------- | ----------- |
 | self    | STRONGLY RECOMMENDED. *Absolute* URL to the location that the Catalog file can be found online, if available. This is particularly useful when in a download package that includes metadata, so that the downstream user can know where the data has come from. |
 | root    | STRONGLY RECOMMENDED. URL to the root STAC Catalog or [Collection](../collection-spec/README.md). Catalogs should include a link to their root, even if it's the root and points to itself. |
-| parent  | URL to the parent STAC Catalog or Collection. Non-root Catalogs should include a link to their parent. |
-| child   | URL to a child STAC Catalog or Collection. |
+| parent  | URL to the parent STAC entity (Catalog or Collection). Non-root Catalogs should include a link to their parent. |
+| child   | URL to a child STAC entity (Catalog or Collection). |
 | item    | URL to a STAC Item. |
 
 **Note:** A link to at least one `item` or `child` (Catalog or Collection) is **REQUIRED**.

item-spec/item-spec.md

@@ -192,8 +192,8 @@ This happens where there is not a clear official option, or where STAC uses an o
 | Type         | Description                                                  |
 | ------------ | ------------------------------------------------------------ |
 | self         | STRONGLY RECOMMENDED. *Absolute* URL to the Item if it is available at a public URL. This is particularly useful when in a download package that includes metadata, so that the downstream user can know where the data has come from. |
-| root         | URL to the root STAC Catalog or Collection. |
-| parent       | URL to the parent STAC Catalog or Collection. |
+| root         | URL to the root STAC entity (Catalog or Collection). |
+| parent       | URL to the parent STAC entity (Catalog or Collection). |
 | collection   | STRONGLY RECOMMENDED. URL to a Collection. *Absolute* URLs should be used whenever possible. The referenced Collection is STRONGLY RECOMMENDED to implement the same STAC version as the Item. A link with this `rel` type is *required* if the `collection` field in properties is present. |
 | derived_from | URL to a STAC Item that was used as input data in the creation of this Item. |