Depends on your version and product.

If you really mean Work Order as in the legacy Work Order module, there aren't business objects (or rather only a couple for reading purposes IIRC) and one of your only options is to query the data through ODBC. 

Refer to the file listing for the Work Order module.

https://help-sage100.na.sage.com/2019/FLOR/#File_and_Table_Listings/WOFileSizes.HTM

If you mean Work Tickets and have Sage 100 Manufacturing (JobOps) installed, IIRC, the data is stored in SO_SalesOrderHeader and SO_SalesOrderDetail and you can query it through ODBC or use SO_SalesOrder_Bus and its Lines object handle property.

If you mean Work Tickets and have Sage 100 Production Management installed, the data is stored in JT_WorkTicketHeader, JT_WorkTicketDetail, and JT_WorkTicketStep and you can query it through ODBC or use JT_WorkTicket_Bus and its Steps and Parts object handle properties.

I'm using "sage 100 Standard 2019" and Version "6.10.0.0"

Created windows application in C# & implemented SO and PO used SO_SalesOrder_Bus & PO_PurchaseOrder_bus and Lines object handle the property. I need to query & check Work order details but not sure what bus I need to query on? Can you please check & help with it?

You have the legacy Work Order module and cannot use BOI to read work order details. 

There is a class called WO_WorkOrder_svc but I have never used it and I think it is only good for reading data in WO1.

Refer to the link in my first response, that list all of the files used along with their table name as seen through ODBC.

You are likely going to be after at least WO1 and maybe WO2 and/or WO3.

do you know how to loop through  the parts? - i am calling the script from the work ticket entry

I tried this - it didnt work

oBusObj.Parts.MoveFirst()
Do
retVAL = oBusObj.Parts.GetValue("ItemCode$", itemcode)

oBusObj.Parts.movenext()
Loop Until CBool(oBusObj.Parts.EOF)

thanks in adcance

You should start a new thread since you appear to have the Production Management module which is entirely different from the legacy work order module that the original poster started this thread about.