formless form - Hindu worhsip of shiva

In Hindu religuos practice Shiva is represented through a Lingam, a phalic stone or pillar. (usually connected with a female "yomi" shaped object).
http://upload.wikimedia.org/wikipedia/c … ouched.jpg
There is some debate as to whether it is a phallus, symbolizing male sex and the male principal or whether it is just an abstraction of a devotional pillar. The debate of course goes along the lines of aniconism and iconism.
http://en.wikipedia.org/wiki/Lingam
Supposedly this symbol has seen several levels of abstraction over the centuries.
There are also natural Lingams, for example ice pillars that form in winter, that are worhsipped as lingams.
It's final formal stage can be seen as resulting in the Akasa Lingam, the representation of Shiav as formless space.
In a temple in the town of Chidambaram, Shiva is worhsipped in his formless form, as a total abstraction.
I am not sure, who the worshipped is performed, but as i understood, there is an insciption, that is blackened, made unreadable, that somehow presents the formless form:

"The temple is supposed to be located at the lotus heart of the Universe: Virat hridaya padma sthalam.
This gold-roofed stage is the sanctum sanctorum of the Chidambaram temple and houses the Lord in three forms:
the "form" - the anthropomorphic form as an appearance of Nataraja, called the Sakala-thirumeni.
the "semi-form" – the semi-anthropomorphic form as the Crystal linga of Chandramaulishvara, the Sakala-nishkala-thirumeni.
the "formless" – as the space in Chidambara-rahasyam, an empty space within the sanctum sanctorum, the Nishkala-thirumeni.

Chidambaram offers a combination of the three apects of Shaiva worship - of the form (Nataraja), of the form and the formlessness (linga) and of the formless omnipresence. The last is suggested by a "Chidambara rahasya", a chakra inscribed on a wall and blackened by applying "punugu" (civet) and over which hangs a string of golden villa (bael) leaves. This can be viewed through the square chinks when the priest draws aside the dark "curtain of ignorance".[51]"
http://en.wikipedia.org/wiki/Thillai_Na … hidambaram