New to LM: How do I refer to the local filesystem in an embedded PowerShell script of a DataSource?

For some reason I'm unable to start a new discussion right now, just says:

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But I've been stumped on the following issue and it's driving me nuts:

How do I read the values of instance-level properties in an embedded PowerShell DataSource Collection script? Or resource-level properties in an embedded PowerShell PropertySource? I understand how to write properties and their values in the Active Discovery script with something like 

Write-Host "<instanceID>##<instanceName>##<instanceDescription>####auto.AssignedCollectorDeviceName=$AssignedCollectorDeviceName"

I have an instance-level custom property "auto.AssignedCollectorDeviceName" on a resource instance that I would like to check the value of during Collection script execution, and create my key-value pair for script output based on that value. But I can't for the life of me figure out how to reference and check the host resource's properties while the script is running.  

Also, my first thought was to have the custom property ("AssignedCollectorDeviceName" in that case) at the resource level, and check it while the Collection scripts runs, but realized I (don't think) I can read a resource-level property in that case, only instance-level properties, but I can't even figure out how to do that (without using the API). So in addition to using the auto property at the instance-level, maybe a PropertySource would be better? I'd like to learn how to make and use one, but in its script I think I would have the same problem of reading the value of resource property in order to do the logic to form the script output.