In this case, it is an action button, and action ID is actualy id of action in database.
In order to find out wich action is triggered by a button you need to take a look at stock_view.xml in stock module.. 
Find a button (reconginze it by string) and take a look at what action is it calling 
You can find some examples arround line 755-756 .. code definig that button could look something like:
<button name="%(action_stock_invoice_onshipping)d" string="Create Invoice/Refund"  attrs="{'invisible': ['|','|',('state','&lt;&gt;','done'),('invoice_state','=','invoiced'),('invoice_state','=','none')]}"  type="action" class="oe_highlight" groups="base.group_user"/>

"%(action_stock_invoice_onshipping)d"  is part you are looking for...

Now you know wich action is triggered.. so you need to search for action_stock_invoice_onshipping in redocrd ids and you will know what you wanted to find out.. 

Hope it helps..