PR #3513, developed by @SaidkhojaIftikhor, has been stuck for some time awaiting tests. This is the second of three PRs to replace that one. This accomodates the use of slash as a delimiter in column names in Tables and Structured References. The source changes are very simple. Additional tests exercise all the source changes.
There is also a preg_quote call when a table is renamed. I have also changed it to accomodate slash, because it's the right thing to do. But ... I can't think how to test it. PhpSpreadsheet will not allow you to set a table name to a string containing a slash (a test is added to confirm), and, if I manually update the Xml in an Xlsx spreadsheet so that the name does contain a slash, Excel will, understandably, complain that the file is corrupt.
oleibman