What those extra Healthcare flags on Oracle SOA 12.1.3.0.5 and 12.2.1 update are for?

Whilst upgrading to 12.1.3.05 I came across the following Post Installation actions at the READ.ME doc of the 22524811 patch:

"4 Post-Installation Instructions"

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2. Add em property : hc.jmsAndDBSameTxn with 'true' value.

3. Following Healthcare Server properties are needed:
        - hc.sequencedEndpoints
                + ALL,<EP_1>,<EP_2> - comman separate value
                + Any endpoints after ALL will not be sequenced.
                + In this example, <EP_1> will have sequcing turned off. <EP_2> will have sequencing turned off.

Note for Bug 20029769:

 hc.HCMode (true/false, default false) - need to set to true

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At the customer, we intended to promote the upgrade to the actual production environment and, because of this, it required further validation of the impacts of such upgrade could bring.

Since the description was not clear enough and I could not find information anywhere else, I raised a service request at Oracle Support for further clarification.

First, I would like to thanks Silviu from Oracle Support for his help and support he have been providing me for the last few years :)

And here are the conclusions of the service request and clarification of the new flags usage:

hc.jmsAndDBSameTxn -  if true, committing to the JMS for customer JMS will be on the same transaction as database.  If database is rolled back, then the message will not be committed to JMS as well. (I'm waiting additional clarification for this point and will add it here once I have it)

hc.sequencedEndpoints - There are two patterns of setting this parameter:

ALL,<EP1>,<EP2> - every endpoints excepts EP1 and EP2 are set to sequencing.
<EP1>,<EP2>,... - every endpoints defined in the property will be set to sequencing.

So, when word ALL is present, any endpoint after ALL will not be set to sequencing.
When word ALL is missing, every endpoint in the list will be set to sequencing.

You can still set the sequencing at the endpoint level configuration from the HC console. This is more a way to set sequencing in multiple endpoints in one shot.

hc.HCMode: this parameter was introduced for fixing a problem (FA_RETRY_TIMEOUT exception) and it's very similar of the parameters b2b.MLLP_HA_Mode=true and b2b.HAInstance=true when these settings are needed when running in clustered environments.

If you enabled it (hc.HCMode = true), then it is not expected you to deploy B2B agreements. If you want to implement MLLP agreements in B2B, and use B2B agreements, then you will have to set hc.HCMode = false.  It's not possible at the same time to use both HC and B2B engines (to deploy B2B agreements and also to activate HC endpoints).