Consciousness is an element among elements conceived & perceived in the world; arises & ceases in the world.
When talking about cessation of perception & feeling it is said;
How many ,conditions are there for the attainment of the theme-less awareness-release?"
"There are two conditions for the attainment of the theme-less awareness-release: lack of attention to all themes and attention to the theme-less property. These are the two conditions for the attainment of the theme-less awareness-release
"There are three conditions for the persistence of the theme-less awareness-release: lack of attention to all themes, attention to the theme-less property, and a prior act of will. These are the three conditions for the persistence of the theme-less awareness-release."
"And how many conditions are there for the emergence from the theme-less awareness-release?"
"There are two conditions for the emergence from the theme-less awareness-release: attention to all themes and lack of attention to the theme-less property. These are the two conditions for the emergence from the theme-less awareness-release."https://www.accesstoinsight.org/tipitaka/mn/mn.043.than.html
Citta asked him a further question: "Now, how does emergence from the cessation of perception & feeling come about?"
"The thought does not occur to a monk as he is emerging from the cessation of perception & feeling that 'I am about to emerge from the cessation of perception & feeling' or that 'I am emerging from the cessation of perception & feeling' or that 'I have emerged from the cessation of perception & feeling.' Instead, the way his mind has previously been developed leads him to that state."
"[...] Citta asked him a further question: "When a monk is emerging from the cessation of perception & feeling, which things arise first: bodily fabrications, verbal fabrications, or mental fabrications?"
"When a monk is emerging from the cessation of perception & feeling, mental fabrications arise first, then bodily fabrications, then verbal fabrications." https://www.accesstoinsight.org/tipitaka/sn/sn41/sn41.006.than.html
On this ground it can be asserted that the duration of the cessation attainment is determined not whilst being percepient of Nibbana but due to a prior act of will and no later than entering.
having directly known the extent of what has not been experienced through the allness of the all, I wasn't the all, I wasn't in the all, I wasn't coming forth from the all, I wasn't "The all is mine." I didn't affirm the all.https://www.accesstoinsight.org/tipitaka/mn/mn.049.than.html
In regards to this it can be asserted that the knowledge spoken about is associated with a meditative attainment on the treshold of supramundane, seeing with wisdom leading to destruction of taints.
Then it can be held that the determination for the duration is an act of will, an occurence in the world, it is included in the allness of the all and isn't made outside of it.
This interpretation holds that emptiness, undirected and theme-less awareness releases are classifications of the cessation of perception & feeling release by which taints are destroyed, are attainments on the treshold of the destruction of taints and the difference is in how they are apprehended in dependence on the perceptions that one developed culminating in the unsurpassed release.
Here from Thanissaro's footnotes to sn41.6;
Emptiness, the signless, & the undirected are names for a state of concentration that lies on the threshold of Unbinding. They differ only in how they are approached. According to the commentary, they color one's first apprehension of Unbinding: a meditator who has been focusing on the theme of inconstancy will first apprehend Unbinding as signless; one who has been focusing on the theme of stress will first apprehend it as undirected; one who has been focusing on the theme of not-self will first apprehend it as emptiness.
This is a pali sutta only interpretation favor by commentary.
I assume this is close to the expression of Mahasi Sayadaw's "Manual of Insight" and still a popular burmese/sri lankan theravadin expression and maybe analysis.
As i ubderstand it;
Suppose 'x' is thought of as a single element, a whole of many sub-elements perceived & conceived in and by itself, X within X is known to be an autonomous self-sustaining, self-creating & self-directing sub-system in and by itself.
Suppose the sub system X, is called thus within Itself because it is not the only element to be known as there is another element which isn't part of the sub-system X, call it Y, which can be known as a truth because cessation of perception is discerned in X in dependence on it.
Knowledge of Y can thus appear as an element included in X if an element of perception within has been directed to cessation.
The factors for arising, persistence & the cessation of the perception of X are included in what is X and are not Y.