efficiency. This does not mean that each office has the same number of file jackets. Rather, it means that a uniform system is used in assigning subject identification numbers, that all general files have the same basic arrangement, and certain types of files are maintained by all activities. Technological advances allow electronic filing of some types of official correspondence on computer diskette. Electronic files are essentially the same as paper files but with one distinct advantage-they allow easy storage and retrieval of large volumes of information in only a fraction of the time and space that would be required for paper files. In practice, there is no difference between managing paper files and managing electronic files. A major disadvantage of electronic document filing is the possibility of frequent power outages and failures. Electronic filing is not practical for every item of correspondence; for example, incoming letters and memorandums. However, other correspondence, such as incoming and outgoing naval messages, can be easily filed electronically. ELECTRONIC MAIL (E-MAIL) Electronic mail (e-mail) provides another means of drafting, stowing, and transmitting correspondence. E-mail allows communication within and between activities, and may be used for informal and formal communication. E-mail also allows users to immediately draft, transmit., or respond to correspondence. E-mail serves the same purpose as a telephone call or letter but, in many cases, is much faster and automatically provides a record of the communication. The transmission and storage of classified or sensitive information by e-mail should be avoided due to security concerns and privacy issues. Refer to the Department of the Navy Correspondence Manual, SECNAVINST 5216.5, for procedures to transmit classified material by e-mail. For e-mail management procedures, refer to the Navy and Marine Corps Records Disposition Manual, SECNAVINST 5212.5 and SECNAVINST 5216.5. FACSIMILE (FAX) TRANSMISSION A facsimile machine or fax is another fast and reliable method of transmitting correspondence, and is an excellent alternative to the U. S. Postal System. The fax telephone number of the activity that is to receive the correspondence is the only information that is required for a user to transmit a copy (facsimile) of a document. Fax copies carry the same weight and authority as the original copy. Some of the same guide- lines set forth for e-mail transmission also apply to fax transmission. The transmission of classified or sensi- tive information should be avoided whenever possible and then only on secure equipment. The cost of sending a fax can be expensive and should be used only for official Government business. Avoid sending graphics whenever possible because they may add to cost. Most activities will have local policies that dictate the use of their fax machines. If you are unsure about what should or should not be faxed, check with your supervisor. MANUAL FILING PROCEDURES When electronic filing and storage of correspondence is neither practical nor desirable, the correspondence requires manual filing procedures. The type of correspondence that is being filed dictates what filing procedures should be used. For example, classified material obviously would not be filed in an unsecured cabinet. Likewise, routine file correspondence should not be filed in a locked safe where access would be limited. Rarely, if ever, will you be tasked with setting up a filing system or selecting filing equipment, however, you should have a working knowledge of the current system and equipment in use in your activity. Whichever filing system or container you use for filing, your correspondence should be filed by standard subject identification code. STANDARD SUBJECT IDENTIFICATION CODES (SSICs) The standard subject identification code (SSIC) is a four- or five-digit number that represents the subject of a document. SSICs are required on all Navy and Marine Corps letters, messages, directives, forms, and reports. SSICs provide a method of filing, identifying, and retrieving documents quickly and consistently. A complete list of SSICs is provided in SECNAVINST 5210.11. There are 13 subject groups under the Navy’s SSIC system. They are as follows: 1000 Series  —Military Personnel 2000 Series  —Telecommunications 3000 Series  —Operations and Readiness 4000 Series  —Logistics 5000 Series  —General Administration and Management 2-20