Add workflows

Author: m-mohr

crosswalks/ogcapi-processes.md

@@ -99,7 +99,7 @@ Some differences include:
   - A link with relation type `http://www.opengis.net/def/rel/ogc/1.0/job-list` to `/jobs` can be
     added in OAP1, but is not present in openEO.
 
-### Conformanc classes
+### Conformance classes
 
 - openEO: `GET /conformance` (optional)
 - OAP1: `GET /conformance` (required)
@@ -298,3 +298,15 @@ In OAP1 the result access [differs depending on the given parameters](https://do
 - OAP1: n/a
 
 As it is neither available in OAP1 nor in any of the OGC APIs, we don't make any comparisons here.
+
+## Workflows
+
+Workflows (user-defined processes in openEO, i.e. processes with process graph) are not described in OGC API - Processes - Part 1. Instead, it's defined in OGC API - Processes - Part 3. It defines how to chain processes in OGC API - Processes and also defines their own "workflow language" ("Modular OGC API Workflow JSON", short: MOAW), but it seems to also allow providing other workflow languages such as openEO user-defined processes and CWL.
+
+Related documents:
+
+- MOAW: https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/sections/clause_6_overview.adoc (and following chapters)
+- openEO: https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/sections/clause_13_openeo_workflows.adoc
+- CWL: https://github.com/opengeospatial/ogcapi-processes/blob/master/extensions/workflows/sections/clause_12_cwl_workflows.adoc
+
+A comparison between MOAW and openEO is tbd.