**DIPS 2/96**[tex source, PostScript, dvi]**Title:**Characteristics of linear differential operators over commutative algebras**Author:**I. S. Krasil'shchikThree definitions for characteristics of linear differential operators in the category of modules over a commutative unitary algebra are given. These definitions are compared with each other and some basic facts concerning their properties are proved. It is shown that for algebras without zero divisors the characteristic ideal is involutive and is the support of the symbolic module.

**To appear**in Acta Applicandae Math.15 pages. LaTeX, XYpic. To compile source files (

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