[SalesForce] What are the object and field name suffixes that Salesforce uses? Such as __c and __x

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A real world use case: I am currently working on a package that allows us to declaratively configure a RESTful architecture parallel to the salesforce standard REST API via Apex REST. This gives us much more control than the Standard REST API over ...

• Setting up resources (defining the path/sub-directory, configure allowed expansions of sub-resources and parent resources and configuring filters)
• Setting up representations (defining the exposed fields of this representations, using different naming conventions for fields (i_like_snake_case) that are independent of the salesforce scheme, exposing only particular relationships (parent/child), and so on)
• Configuring individual representations for each HTTP-Verb (GET,POST,PATCH,etc) per Request/Response (say, you expect only 3 mandatory fields for a POST Request, but you always want to render all 15 mapped fields in a Response to this POST and use a completely different representation in a Response to a GET)

All of this functionality is fully generic, and I implemented this by making extensive use of Custom Metadata Types. To summarize:

• The key Metadata Objects are Resources, Representations and Representation Properties
• A representation maps to a certain SObject, so there is a custom field on the metadata type "SObject__c" of the type Entity Definition where you define a particular SObject (that will be used to dynamically generate the SOQL-Query string)
• Representation has a related list of Properties, where we configure all the properties (meaning "keys" of the rendered json): In a Property, I essentially define a field mappings: The external name (i.e email) and with a Field Definition field, the salesforce field (ArbitraryBusiness_Email__c) that will be used to retrieve/store the data.

All SOQL queries to retrieve the records (during GET calls) and DML to perform more complex operations (especially PATCH and POST) is generated dynamically, fully generic during runtime based on the meta data records.