法華玄義釋籤 2.24

2.24

次引大經證中云「或時說深、或時說淺等名不定」者，以由彼此互相知故。若祕密者，即如下文互不相知，是故名密。不定與祕並皆不出同聽異聞，故名為即。今亦淺深同席，故著「或」言。「應問」謂開其問端，「應遮」謂置其所問，亦開置同席故成不定。

Next, in quoting the Great Sūtra as verification, where it says 'sometimes preaching the profound, sometimes preaching the shallow, and so on, is called indeterminate,' this is because they mutually know each other. If it were secret, then as the text below says, they would not mutually know each other, which is why it is called secret. Both the indeterminate and the secret do not go beyond hearing different things while listening together; hence they are said to be identical. Here too, the shallow and profound share the same seat, which is why the word 'sometimes' is used. 'Should ask' refers to initiating a point of questioning; 'should check' refers to setting aside what was asked; because initiating and setting aside share the same seat, this constitutes the indeterminate.