It is vital for the success of a software project to construct a complete and concise requirement document in the early development phase. Tabular Expressions can be used to formally define software technical documents and achieve both conciseness and readability. SCR method is a practical document-driven requirement method which has gained widespread applications. Three special tables have been utilized in the SCR method for facilitating requirement documentation. This paper gives formal definitions of SCR tables within the new mathematical model of tabular expression. Especially, a general way to defining timing properties for large complex systems is proposed. Problems with SCR table definitions are pointed out. It is indicated that the new mathematical model of tabular expressions is not only general enough to include SCR tables, but also provides a sound support for formal documentation.