Transliteration and the fold

Explanation, not scripture — scholar review pending. These pages explain the scripture to engineers and students. Every quoted line is verbatim from the pinned database and cited by Ang; everything else is explanation, written by engineers and awaiting a Granthi’s review. Where this page and the scripture differ, the scripture is right.

Beside every line the database keeps a transliteration — the line in Roman letters, built by the pipeline from the Gurmukhi:

ੴ ਸਤਿ ਨਾਮੁ ਕਰਤਾ ਪੁਰਖੁ ਨਿਰਭਉ ਨਿਰਵੈਰੁ ਅਕਾਲ ਮੂਰਤਿ ਅਜੂਨੀ ਸੈਭੰ ਗੁਰ ਪ੍ਰਸਾਦਿ ॥
ik oankaar sat naam karataa purakh nirabhau niravair akaal moorat ajoonee saibhn gur prasaad
— Sri Guru Granth Sahib Ji · Ang 1

It is a reading aid for people who do not read Gurmukhi, and a search key. It is not scripture: it is never cited, never verified, never shown alone. Several Roman schemes exist and none is canonical; the pipeline’s is consistent, and that consistency is what search needs.

What the fold is for

Seekers type a Gurmukhi word the way they hear it: waheguru, vaahiguroo, wahegurooh. A search that demanded the pipeline’s exact spelling would miss most of them. The fold — roman_norm — reduces every spelling of a word to one key by five rules (letter substitutions, digraphs, voicing pairs, the y glide, vowels dropped and doubles collapsed), so waheguru and vaahiguroo both become vhgr. The database stores the folded form of every line’s transliteration (translit_norm), and the query is folded the same way at search time.

The fold is deliberately lossy: it trades precision for recall, which is why the search waterfall tries it only after the exact tiers, and why the verification engine uses it to find candidates but scores them with the full transliteration before deciding a verdict.

One function, three homes

The same fold must run wherever a key is made: in sggs-data when the database is built, in the platform at query time, in the app on the device. Three copies, held byte-identical by 24,719 golden vectors — the whole story, with the function read from the source, is The Roman fold.

What to remember

• Show the transliteration under the Gurmukhi and in a lighter style; never in place of it.
• Never cite a transliteration; cite the Gurmukhi line by Ang.
• Never “improve” the transliteration scheme in one place: it is an index, and a change is a coordinated dataset release.
• A seeker’s misspelling is the fold’s job, not the reader’s: the first-letters and skeleton tiers exist for the same reason.

Read next: The Answer Protocol for engineers.