The popularly taught three marks of existence (trilakṣaṇa), namely, anitya (not eternal or everlasting), duhkha (disharmony/suffering), and anatman (no atman), come under the heading of the conditioned. We have to understand that these three marks only address the finite world, never the transcendent world (paraloka). Less discussed, if at all, there is another passage by the Buddha which describes “three conditioned marks” which refers to a conditioned state.
“Monks, there are these three condition-marks of that which is conditioned. What three? Its genesis is apparent, its passing away is apparent, its changeability while it persists is apparent. These are the three condition-marks” (AN 3:47).
We have to understand that the conditioned leaves out the unconditioned (one of those no brainers) such as nirvana, the unborn, the immortal-element, etc. We also have to put anitya, duhkha, and anatman under the heading of conditionality—never the unconditioned. Now here is where a problem comes as I see it. Many Buddhists, including teachers, have a bad habit of making anitya, duhkha, and anatman, the alpha and the omega if not the all encompassing, putting into this triad even the unconditioned, i.e., nirvana! They don’t understand that the three marks are rather a limit. They are absent of the eternal, felicity, and atman all of which characterize the unconditioned.
The Buddha’s discourses use a lot of words explaining to us what we should transcend—not covet or cling to. But there is also a chapter on the unconditioned in the Samyutta-Nikaya where the Buddha teaches, for example, “the path leading to the unconditioned” (S. iv. 360). In the same chapter the Buddha says the Noble Eightfold Path is the path leading to the unconditioned (S. iv. 361). And important part of the Noble Eightfold Path is “right view” which the Buddha says is supermundane (M.iii.72). We can put the supermundane into the category of the the unconditioned.
Needless to say I am suspicious that three marks are being used today in a kind of confidence game, in order to convince the public that Buddhism rejects any kind of absolute (i.e., the unconditioned).