Without 'to be' it's only a subclause. For example, "the documents being requested", "new tires being manufactured in Iowa" and "Raspberry pie being manufactured in the UK" are not full sentences. 1) is correct because it has the verb 'specify', but 2) and 3) need to add a verb to be full sentences. "The book being read", "The pancakes being made" and "The hydraulic motors being manufactured", in addition to the examples above, are all treated as one noun in a sentence, and mean nothing by themselves. Examples of full sentences: "New tires are being manufactured in Iowa." "New tires being manufactured in Iowa are well made." "Raspberry pie being manufactured in the UK is very delicious." "Raspberry pie is being manufactured in the UK." "The book being read is very good." "The pancakes being made look delicious." etc. By the way 'pi' refers to the mathematical number 3.1427... 'Pie' refers to the food. :-)