Analysis of information sources in references of the Wikipedia article "BCPL" in Chinese language version.
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Historically BCPL used the symbols$(and$)to bracket commands and declarations. These symbols are called section brackets and are allowed to be followed by tags composed of letters, digits, dots and underlines. A tagged closing section bracket is forced to match with its corresponding open section bracket by the automatic insertion of extra closing brackets. Use of this mechanism is no longer recommended since it often leads to obscure programming errors. BCPL has been extended to allow all untagged section brackets to be replaced by{and}as appropriate.
