This book is based on my research and translations of the ancient literatures, the conclusions that I have drawn based on my translations, as to what Shiva possibly could have meant. You can read the translations at my blog https://ancientinsight.online.
At a very high level, a contextual translation of the ancient literatures indicate that Shiva is the environment that gets created due to the vibration(OM) yielding to the turbulence (Rudra) that is present in the Isha (a set of potentials). A constriction in the entanglement (created due to the turbulence), creates a Linga and causes a part of the vibration (OM) to hang perpendicular to this system. These vibrations circle over themselves and come back and meet the entanglement, creating an environment of directed and reflected vibrations which then supports the formation of impulses which then grows to become awareness and beings. This environment is sustained by the Linga and the turbulence each ensuring that the other does not fade away.
The book follows through from the Bhagavad Gita’s Kshetra-Kshetragyana-Yoga (Chapter 13) that describes the environment, the nature of the become and the soul of the becoming, to the Kalabhairava Ashtakam that describes the dimensions of the awareness to the Shiva Tandava sthotram that describes the creation of this environment, to show why Shiva actually is a concept and is the environment that is formed.