Sentence:  For internal political reasons , the union asks for ( and accepts ) increases in the basic wage rate , and would vigorously oppose a reduction in this rate , but the adjustment of the basic wage rate upwards is <WSD>essentially</WSD> up to the discretion of the companies of the industry . 
Meaning of the word marked with <WSD> tags:  in essence; at bottom or by one's (or its) very nature