Still open questions

I came here to learn when Post() will return true, and when it will false.

But now, I have more questions and still no answer:
- "This method will return once the target block has decided to accept or decline the item", yes, but HOW?
Does "accept" mean added to the target's queue?
- When a filter denies, will then false be returned?
- Within a custom block - can I deny the message during processing? How?

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* ID: 054efdcd-9fa5-f955-3fc7-53101b797428
* Version Independent ID: 7269c09f-894e-a6ee-b7dc-0f53118004fc
* Content: [DataflowBlock.Post(ITargetBlock<TInput>, TInput) Method (System.Threading.Tasks.Dataflow)](https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.dataflow.dataflowblock.post?view=netcore-2.2#System_Threading_Tasks_Dataflow_DataflowBlock_Post__1_System_Threading_Tasks_Dataflow_ITargetBlock___0____0_)
* Content Source: [xml/System.Threading.Tasks.Dataflow/DataflowBlock.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Threading.Tasks.Dataflow/DataflowBlock.xml)
* Product: **dotnet-api**
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* Microsoft Alias: **dotnetcontent**