Guhya[kālī]ṣoḍhā/Guhyaṣoḍha, would mean a text featuring a sequence of mantras that a tāntrika would need to recite in order to "purify" himself and the mantra, which would precede the recitation of the root-mantra of the deity.
Here we have a long sequence, consisting with 12 subsequences, in which the bījas (seed-syllables) of the mūlamantra (i.e. root mantra, given on f. 1v.) are envelopped in and are envelopping in various ways the letters of the alphabet. These letters are 51: a ā i ī u ū ṛ ṝ ḷ ḹ o au aṃ aḥ ka kha ga gha ṅa ca cha ja jha ña ṭa ṭha ḍa ḍha ṇa ta tha da dha na pa pha ba bha ma ya ra la va śa ṣa sa ha la kṣa. The last 2 letters are untypical. If kṣa is added to the tantric alphabet (mātṛkā) as early as the 11h-12th century (evidence based on the earliest manuscripts of the Kubjikāmatatantra, the Ṣaṭsāhasrasaṃhitā and the Jayadrathayāmalā), the additional la (likely to mean modern ळ), clearly indicated that the text, although written in Sanskrit, has the influence of modern languages of North- western India, such as Marathi or Rajasthani. The fact that the manuscript with the same names has been attested in Ujjain favors this conclusion as well.
The text claims its relation to the Rudrayāmala in the colophon.
The Rudrayāmala is originally a very ancient tantric text; the first mentions of might belong to the original Skandapurāṇa, chapter 171, v. 129cd, where it occurs under the name "aiśāna" that is Īśāna(yāmala). That would be another name of Śiva just like Rudra. (see notes in Serbaeva 2006, Ph.D., unpublished, p. 26, it is certainly mentioned in the Brahmayāmala 39.35cd, Jayadrathayāmala 1.36.19ab, 1.44 throughout and 3.24.36cd, Siddhayogeśvarīmata 29.17.cd, Vijñānabhairava, verses 1 and 161; the evidence of the Brahmayāmala and the Siddhayogeśvarīmata places the Rudrayāmala before 8-9th century AD.). However, that original text has never been found. Multitude of later texts (the New Catalogus Catalogurum vol. 25 lists a few hundred) attributes themselves to that mythical Rudrayāmala, no doubt, in order to gain authority.

• 1r : Guhyakālīyā svāhā "Svāhā to Guhyakālī", svāhā is a ritual exclamation in the context of fire-offering. Guhyakālīṣoḍhā: this is a name of the text. In the text is written as Guhyaṣoḍhā. We should accept in this case Guhyakālīṣoḍhā as the full title and Guhyaṣoḍhā as its abbreviated variant.
• 1ra [handwriting and pen is different (20th century) from the main body of the manuscript]: mamastayasta [dha]rmmim[a]. The first part of this is likely to mean sanksrit mamasatya, i.e. claim of ownership, the [Dha]rmmim[a] is likely to mean Dharmiṇa[s] to refer to the name of the owner, Dharmin. And something was written and defaced, the inscription is not visible.
• 3r Incipit oṃ namaḥ śrī gu[+ru]ve // atha guhyaṣoḍhā likhyate // tad uktaṃ rudrayāmale
• 22r : Guhyakālīṣoḍhā
• 3v explicit: maṃ 5 x 2// 5 x yaṃ 5 x 2 // 5 x caṃ 5 x 2// 5 x laṃ 5 x 2 // 5 x vaṃ 5 x 2 // 5x śaṃ 5 x 2 // 5 x ṣaṃ 5 x 2 // 5 x saṃ 5 x 2 // haṃ 5 x [+2] // 5 x laṃ 5 x 2 // 5 x kṣeṃ 5 x 2
• 3v colophon: iti śrīrudrayāmale guhyaṣoḍhā samāptaṃ // śrīyogarājena likhitāḥ // śubhaṃ bhūyāḥ // śrī 3 mad ekajaṭā prītir astu // Here ends the [chapter] on the purification of the mantra of the Secret [Kālī] [i.e. Guhyakālī] belonging to the glorious Rudrayāmala. It was written by Glorious King of Yoga. Let is be auspicious. Let it be pleasing to three times glorious Ekajaṭā.
• 2v Mulamantra Śrī guhyakālyai // oṃ aiṃ āṃ hrīṃ phreṃ cchrīṃ hūṃ strīṃ siddhikālālyai aparājitā puṣpaṃ samarppayāmi namaḥ svāhā //oṃ aiṃ hrīṃ śrīṃ klīṃ āṃ hūṃ strīṃ phreṃ khphreṃ bhagavatī vajrakāpāli breaks off or unfinished, can also be read at the very top as a summary of the whole, featuring the mūla-mantra
  
  • A catalogue of Manuscripts in the Oriental manuscripts library (Prācya Grantha Saṅgraha, now called Scindia Oriental Institute), Ujjain, Vol. 1, 1936; Vol. 2, 1941.

  • Muktabodha: www.muktabodha.org
  • New Catalogus Catalogorum. An alphabetical register of Sanskrit and allied works and authors, Madras: University of Madras, 1949 -. v. 1-39 (Madras University Sanskrit Series). Vol. 25: rāmāyaṇa-rauhiṇeyakathā, published in 2011, editor-in-chief Siniruddha Dash.)
  • Serbaeva, Olga, Yoginīs in Śaiva Purāṇas and Tantras: Their role in transformative experiences in a historical and comparative perspective, Ph.D. University of Lausanne, submitted 03.07.2006, unpublished, p. 26.