In GE1 (→GE2), there is only one 
in bar 285 instead of three subsequent 
marks. There are no doubts that it is a mistake; however, it remains a mystery how such an accumulation of mistakes occurred (moreover, three out of four in analogous bars 299-302 were overlooked). Perhaps some of them, e.g. those in bars 299-302, were added only just in the last proofreading of FE. GE3 added in all five bars devoid of the marks.
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category imprint: Differences between sources
issues: Errors in GE, GE revisions
notation: Verbal indications