It seems like there were no source files for most of Dyalog APL's history. Instead, images held code and variables. You would pass them around to work with other people. While there are features such as LINK nowadays that make this irrelevant, one can stumble upon forum posts on how to share or run code with images in bewilderment.
Стало известно о неспособности Пентагона расследовать удар по иранской школе08:35。业内人士推荐新收录的资料作为进阶阅读
，这一点在新收录的资料中也有详细论述
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You don't hear from them again.，更多细节参见新收录的资料