【正文】 multihomed stub domains will have more than one edge to a transit domain. ELS, the average number of edges from a LAN to a stub node. Every LAN must be connected to at least one stub node, thus ELS= 1. LANs may be connected to more than one stub node in the assigned stub domain. Generation Process Knowledgework level: Advisors to both top and middle management who are often experts in a particular area. Tactical level: Middle managers who deal with planning, anizing and the control of the anization. Strategic level: Strategic managers who make decisions that guide the manner in which business is done. Each successively lower level has different OIS requirements and a different, and less extensive, view of the anization. Obviously, the higher the level, the more interrelated the business functions bee until, at the very top, they are viewed as one homogeneous anization with one continuous data flow. Office automation systems can be effectively utilized in all the clerical, operational, knowledgework, tactical, and strategic levels, as illustrated in Fig. 2. They can assist workers who work with word processors, electronic mail, and spreadsheets to use, manipulate, disseminate information, and help managers in planning, anizing, control and taking decisions. OFFICE AUTOMATION SYSTEMS Typical office automation systems handle and manage documents through word processing, desktop publishing, document imaging, and digital filing, scheduling through electronic calendars, and munication through electronic mail, voice mail, or video conferencing. In this section, 18 different types of OIS are discussed and described that are classify into four categories: productivity tools, digital munication systems, groupware applications, and teleconferencing 12 systems (Fig. 3). Figure 2. Support of OIS to the different anizational levels Figure 3. Office information systems Productivity Tools Productivity tools are software programs used to create an end product, such as letters, s, brochures, or images. The most easily recognized tool is a word processing program, such as Microsoft Word or Corel WordPerfect. Other tools help you view, create and modify general office documents such as letters, spreadsheets, memos, presentations, and images. Word Processing. Of all puter applications, word processing is the most mon. Almost every puter has a word processing program of some kind: whether it came free with the operating system or whether it was purchased separately. In order to perform word processing, it is necessary to acquire a puter, a word processor, and a printer. A word processor enables you to create a document, store it, display it on the puter screen, modify it, and print it using a printer. There are many different word processing programs available, each offering different tools that make it easier to write everything from letters and term papers to theses and Web pages. 13 Most people use a word processor rather than a typewriter because it allows greater flexibility and control. It is possible to make changes without retyping the entire document. If mistakes are made while typing a text, the cursor can be used to correct errors. Word processors allow text rearranging, changing the layout, formatting the text, and inserting pictures, tables, and charts. Most word processors available today allow more than just creating and editing documents. They have a wide range of other tools and functions, which are used in formatting documents. The following are the main features of word processors: Insert, delete, copy, cut, and paste text: Allow to insert, erase, and copy text anywhere in the document. Cut and paste allow removing (cut) a section of text from one place and inserting (paste) it somewhere else in the document. Search and replace: Allow searching for a particular word and also replacing groups of characters. Font specifications: Allow to change fonts within a document. For example, you can specify bold, italics, font size and underlining. Graphics: Allow adding pictures into a document. Captions and crossreferences: Allow placing captions to describe tables and pictures and creating references to them anywhere in the document. Page setup, headers, and footers: Margins and page length can be adjusted as desired. Allow to specify customized headers and footers that the word processor will put at the top and bottom of every page. Layout: Allows specifying different margins within a single document and to specify various methods for indenting paragraphs. Spell checker and thesaurus: Spelling can be checked and modified through the spell check facility. The thesaurus allows the search for synonyms. Tables of contents and indexes: Allow creating table of contents and indexing. Print: Allows sending a document to a printer to get a hardcopy. Spreadsheet. A spreadsheet is a puter program that presents data, such as numbers and text, in a grid of rows and columns. This grid is referred to as a worksheet. You can define what type of data is in each cell and how different cells depend on one another. The relationships between cells are called formulas, and the names of the cells are called labels. There are a number of spreadsheet applications on the market, Lotus 123 and Microsoft Excel being among the most famous. In Excel, spreadsheets are referred to as workbooks and a workbook can contain several worksheets. An example of an Excel worksheet is shown in Fig. 4. Desktop Publishing. Desktop publishing is the use of the puter and specialized software to create high quality documents for desktop or mercial printing. Desktop publishing is the process of editing and layout of printed material intended for publication, such as books, magazines, brochures,