3.4 Phrase structure rules listed (Western). PS-RULES are often combined together when they share the same symbol on the left side. Hence, rule P4 describes two main constituencies for the number phrase (NUM). The use of parentheses is also to enclose optional elements. This means that P4 is really three rules and P1 not just four, but actually a total of eleven different ways to rewrite a DNP. Note that the immediately following rules are designed for English. The intended interpretation for the elements corresponding to these symbols, while appearing in brief in the previous paragraph, are found in more detail in the glossary.