# What is CSA* queue
Ross asked why there is strange queue with name CSA* in inbound or outbound queue monitor.
There is already good answer from SCN:
http:// scn.sap.com/thread/2079 157
Basically speaking, every time you make changes on an object in CRM downloaded from ERP, there will be CSA queue automatically generated.
Those queue is responsible to synchronize this CRM change to other site which has registered this change. ( Note: other site does not mean ERP here! )
Before line 167 is executed, BDOC state is below:
After line 167 is executed, notice the BDoc state change:
In line 9 here, all registered listener who are intrested with this CRM change are executed within loop:
For BDOC HIERARCHY_PROD, there are three registered listeners:
These listeners are executed within loop.
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