同上符号（〃）是一个用于印刷的标点符号，表示前述的内容将会重复。例如：

其缩写"do."源自"ditto"，这个词来自意大利托斯卡纳语，它是动词"dire"（说）的过去分词，有「已提及」之意。在英语，以此解作「同上」的记录最早出现在1625年。早期使用同上符号的证据可在新亚述帝国时期（前934 – 608）的楔形文本的文献中找到，其中用两条竖线标示与上文重复的话，在中国，这个符号写作两条横线（＝），参见叠字符号。

在法律文档中，使用同上符号、其缩写或本字"ditto"往往是明文禁止的。

The ditto mark (″) is a typographic symbol indicating that the word(s) or figure(s) above it are to be repeated. For example:

The word ditto comes from the Tuscan language, where it is the past participle of the verb dire (to say), with the meaning of “said”, as in the locution “the said story”. The first recorded use of ditto with this meaning in English occurs in 1625. Early evidence of ditto marks can be seen on a cuneiform tablet of the Neo-Assyrian period (934 – 608 BC) where two vertical marks are used in a table of synonyms to repeat text, while in China the corresponding mark is two horizontal lines (二); see iteration mark.