Update FAQs with more questions and answers from...

Update FAQs with more questions and answers from https://gitlab.version.fz-juelich.de/maestro/maestro-core/-/issues/29
in README.md

README.md

@@ -196,6 +196,23 @@ Doxygen documentation is available and compiled in [docs](./docs) folder.
   is a chance that your firewalling intercepts the packages.
 
   
+* ##### Is it safe to invalidate the pointer to data wrapped by an offered cdo, given that ownership has passed to maestro core? (We keep hold onto the cdo handle itself of course.) 
+   No, the allocation that was captured in the cdo handle must not be touched until after DISPOSE. Of course you can forget the pointer you have, but you must not re-use the allocation or free it.
+
+* ##### Does a producer have to check whether an offered cdo has been consumed (DEMANDed), and wait until it is, before calling (withdraw followed by) dispose?
+   A producer cannot directly figure that out (unless you do complicated event ops). The idea is: The consumer must submit the REQUIRE before the WITHDRAW occurs. This can be accomplished by
+      1. pre-posting the REQUIRE, or
+      2. by posting it after observing an OFFER:before or OFFER:after event (for safety with a 'require-ack' flag or any earlier event, like DECLARE or SEAL),
+      3. by posting it in a WITHDRAW:before with require-ack set.
+   In all these cases Maestro will ensure that the REQUIRE can be satisfied, by taking a copy (more or less eagerly, this is to be tuned], or by blocking WITHDRAW.
+
+* ##### Should withdraw be needed at all if an offered cdo is consumed by another application?
+  Every OFFER must be followed by WITHDRAW (and DISPOSE); every REQUIRE must be followed by RETRACT or DEMAND (and DISPOSE). Remember that one OFFER can satisfy many REQUIRES for the same CDO; WITHDRAW indicates that you're no longer ready to do so (and maestro needs to ensure outstanding REQUIRES can still be satisfied if their DEMAND comes in) 
+
+* ##### Should dispose block until an offered cdo is consumed by another? Or will it only block if there has already been a require posted?
+   WITHDRAW may block if maestro decides that it cannot or does not want to take a copy and there is at least one outstanding REQUIRE for the CDO, or a DEMAND is still in progress. DISPOSE should never block (but may take some time -- but not related to the pool protocol).
+
+
 # Authors and acknowledgment
 
 [Data Orchestration in High Performance Computing](https://www.maestro-data.eu/) project has received funding from the European Union’s Horizon 2020 research and innovation program through grant agreement  801101.