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The article presents a partial dossier on distinguishing between handwritten zero and the letter "oh." Most standard typewriters make no distinction between the "oh" and the zero. In fact, some do not have a key for the zero, relying upon the capital "oh" instead. This is a convention rooted in time. A great deal of handset type and some typewriters differentiate by making the "oh" fatter and rounder while the zero remains a narrow oval. Some fonts have distinguished even more by making the "oh" squarish. Such a difference in character width affords partial distinction; it requires a size discrimination from the reader which requires more concentration than graphic discrimination. The slash has been used to distinguish between the "oh" and the zero. The only problem is that users have been inconsistent in deciding which of the two should be slashed. It is the existing and preferred practice that, on devices such as printers and typewriters, the character shapes for zero and oh be sufficiently different and distinguishable.