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signature,in music: see musical notationmusical notation,
symbols used to make a written record of musical sounds.
Two different systems of letters were used to write down the instrumental and the vocal music of ancient Greece. In his five textbooks on music theory Boethius (c.A.D. 470–A.D.
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signatureA group of spectal lines usually in an emission spectrum that identifies a chemical – an atom or molecule, possibly ionized and/or in a rare isotopic form – in a star, stellar environment, galaxy, etc.
in mathematics, a number characterizing a quadratic form. Every quadratic form with real coefficients can be reduced by a nonsingular linear transformation of variables with real coefficients to the form
The difference ρ – q between the number of positive and negative terms in this expression is called the signature of the quadratic form. The numbers ρ and q are independent of the means by which the quadratic form is reduced to the form (*).
a number placed at the lower left-hand corner of the first page of each sheet of printed pages and repeated with an asterisk on the third page. The signature is used as a control in arranging the sections of a publication before binding.
ii. As it relates to air-photo interpretation, it is the visual characteristics of objects on an air photograph that allow one to differentiate them. These characteristics include the tone, shape, size, pattern, texture, and shadow. Tone refers to the relative brightness or colors of an object in an image. Generally, tone is a fundamental element for distinguishing between different targets or features. Variations in tone also allow the elements of the shape, texture, and pattern of objects to be distinguished. Shape refers to the general form, structure, or outline of individual objects. Shape can be a very distinctive clue for interpretation. Straight-edge shapes typically represent urban or agricultural targets, whereas natural features, such as forest edges, are generally more irregular in shape. The size of objects in an image is a function of scale. It is important to assess the size of a target relative to other objects in a scene to aid in the interpretation of that target. Pattern refers to the spatial arrangement of the visibly discernible objects. Typically, an orderly repetition of similar tones and texture will produce a distinctive and ultimately recognizable pattern. Orchards with evenly spaced trees and urban streets with regularly spaced houses are good examples of pattern. Texture refers to the arrangement and frequency of tonal variation in a particular area of the image. Rough textures would consist of a mottled tone where gray levels change abruptly in a small area, whereas smooth textures would have very little tonal variation. Shadow is also helpful in interpretation, as it may provide an idea of the profile and relative height of a target(s).
A signature should give your real name and your e-mail address since, though these appear in the headers of your messages, they may be munged by intervening software. It is currently (1994) hip to include the URL of your home page on the World-Wide Web in your sig.
The composition of one's sig can be quite an art form, including an ASCII logo or one's choice of witty sayings (see sig quote, fool file). However, large sigs are a waste of bandwidth, and it has been observed that the size of one's sig block is usually inversely proportional to one's prestige on the net.
See also doubled sig, sig virus.
signature(1) See digital signature and email signature.
(2) A pattern used for matching. Also called a "fingerprint" or "definition." For example, antivirus companies maintain a database that contains the virus code (the signature) of each of the known viruses. To detect a virus, the antivirus program looks for these code strings in executable programs. Spyware blockers that look for spyware and adware also use signature patterns.
An intrusion detection system also uses signatures, which are patterns that suggest an attack. For example, excessive logins that failed or the execution of certain programs.
(3) A unique number built into hardware or software for identification.
(4) A group of printed pages used in the construction of a book or booklet. Typically comprising 16 or 32 pages, signatures may also be 8, 12, 24, 48 or 64 pages long. The signature is printed on one large sheet of paper in a certain "imposition" order that, when cut and folded, results in the correct page sequence. The signatures are then bound together to make the final product.