The 36 saiva tattvas

saMkhya (based on the saMkhya kArika of Iswara krishna) design pattern has 24 elements excluding the purusha.

Basically it's a design pattern for evolution in matter and consciousness domain. The design pattern is "A detached observer drives the evolution of the evolute". Observer is purusa. evolute is prakrti. 

For eg we define a parameter called 'energy' which is abstract, but which is known through its effects such as mass, heat, motion etc. we attribute one cause called 'energy' to all these effects, because they are transformable between each other. We say they express the same 'energy'.  The abstract energy is the 'puruSa' the observer.  All the matter and biological forms are the prakrti, the evolute.

Same way we define a parameter called 'consciousness' which is abstract, but which is known through its effects such as signaling, growth, death etc,  We attribute one cause called 'consciousness' to all these effects, because they are transformable (or drive) each other. We say they express the same 'consciousness'. The abstract consciousness is the puruSa the observer. The evolution of self, manas, indriyas etc is the prakrti the evolute.

This is what is explained in saMkhya kArika as a design pattern for evolution involving prakrti(1), mahat(1), ahamkara(1), panchabhutas(5), pancha tanmatras(5), dasa indriyas(10) and manas(1). The 24 elements are the saMkhya philosophy.

The 25th element is puruSa. 

But Brhadharanyaka Upanishad says puruSa manifests in 5 ways in the 5 yajnas. 

In nature, there are 5 domains. 1. Energy 2. Mass 3. Matter forms in classical world 4. Consciousness as in biological forms 5. Our mind or manas.

We saw earlier, how energy and consciousness are abstract 'observer' terms. In a chemical reaction catalyst functions as observer in the classical matter world. In mass, the higgs self-coupling constant functions as an observer causing mass in all particles. The conscience or manas-sAksi is the observer in our mind or manas.

These are the pancha mahA-puruSas.  But all the  5 are manifestations. Hence they are said to be mAyA.

Brhadharanyaka upanishad says the Universe originated when the purusha tore apart the stri from itself due to its desire. That stri is the prakrti. Ultimate underlying aspect of Universe beyond all manifestation is the energy or consciousness or whatever that gets expressed through the manifestations of the Universe. That is the Shiva.

Shiva is the energy, consciousness, the ardhanareeswara, from whom Universe manifests in the vedic tattvas (also in the saiva tattvas).

The five puruSas, the five stris of each puruSa, 24 elements of saMkhya make the 34 elements of saiva tattva. But saiva tattva also enumerates the overall puruSa and Stri (though they manifest in 5 different ways) as 2 separate  elements and make it 36 tattvas.

These are just the interpretations of the same underlying philosophy at different points of time by different people.