Hi all . As am currently going through the book " Unicode Standard Version 6.1 Core Specification - Chapter 9", the upcoming blogs can be truely informative for the South Asian scripts namely Devanagari, Gujarati, Kannada & Malayalam. It may come in series format just like the present one is specifically for devanagari.
2. Encoding Principles :
The writing systems constitute cross between syllabic & alphabetic writing systems. The effective unit of these writing systems is the orthographic syllable, consisting of consonant & vowel (CV) core & optionally with a canonical structure of (((C)C)C)V.
3. Rendering Devanagari :
>>Rules For Rendering :
R1
When nominal consonant preceeds a VIRAMA, it is considered to be a dead consonant . A consonant that does not precede VIRAMA is considered to be a live consonant .
TAn + VIRAMAn -> TAd
त + ् -> त्
R2
If ra+virama precedes a consonant , then it is replaced by superscript nonspacing mark "repha".
RAd + KAl -> KAl + RAsup
र् + क -> क + र् -> र्क
R3
If the "repha" is to be applied to a dead consonant & that dead consonant is combined with another consonant to form a conjunct , then the mark will be applied to the conjunct ligature form as a whole .
RAd + JAd+ NYAn -> J.NYAn +RAsup
र् + ज् + ञ -> ज्ञ +र् -> र्ज्ञ
R4
If the "repha" is to be applied to a dead consonant that is subsequently replaced by its half-consonant form, then the mark will get applied to the base of consonant cluster.
RAd + GAd + GHAl -> GAh + GHAl + RAsup
र् + ग् + घ -> ग् + घ + र् -> र्ग्घ
R5
In conformance with ISCII std , the half-consonat form is represented as eyelash-RA . This form of RA is commonly used in writing Marathi .
RRAn + VIRAMAn + YAn -> RRAh
ऱ + ् + य -> ऱ्य
RAd + ZWJ + YAn-> RAh
र् + + य -> ऱ्य
R6
Except for dead consonant RA, when a dead consonant precedes the live consonant RA,then dead consonant is replaced with its nominal form, and RA is replaced by subscript RAsub, which applies to nominal form.
TTHAd + RAl -> TTHAn + RAsub
ठ् + र -> ठ + ्र -> ठ्र
R7
For certain consonants, the mark RAsub may graphically combine with the consonant to form a conjuncts.
PHAd + RAl -> PHAn + RAsub
फ् + र -> फ + ्र -> फ्र
R8
If a dead consonant (other than RAd) precedes RAd, then the substitution of RA for RAsub is performed ; however, the VIRAMA that formed RAd remains to form a dead consonant conjuct form.
TAd + RAd -> TAn + RAsub + VIRAMAn -> T.RAd
त् + र -> त + ्र + ् -> त्र ्
R9
The nukta sign, which modifies a consonant form, is attached to that consonant in rendering. If the consonant represents a dead consonant, then NUKTA should precede VIRAMA .
KAn + NUKTAn + VIRAMAn -> QAd
क + ़ + ् -> क़्
R10
Other Modifying marks , in particular bindus , apply to the orthographic syllable as a whole. The bindus should follow any vowel signs. The relative placement of these marks is horizontal rather than vertical; the horizontal rendering order may vary according to typographic concerns.
KAn + AAvs + CANDRABINDUn
क + ा + ँ -> काँ
R11
If a dead consonant immediately precedes another dead consonant or a live consonant, then the first dead consonant may join the subsequent element to form a two-part conjunct.
JAd + NYAl -> J.NYAn
ज् + ञ -> ज्ञ
TTAd + TTHAl -> TT.TTHAn
ट् + ठ -> ट्ठ
R12
A conjunct ligature form can itself behave as a dead consonant & enter into further, more complex ligatures. A conjunct ligature form can also produce a half-form.
SAd + TAd + RAn -> SAd + T.RAn -> S.T.RAn
स् + त् + र -> स् + त्र -> स्त्र
R13
If a nominal consonant or conjunct ligature form precedes RAsub as a result of the application of rule R6, then the consonant or ligature form may join with RAsub to form a multi-part conjunct ligature.
KAn + RAsub -> K.RAn
क + ्र -> क्र
R14
In some cases, other combining marks will combine with a base consonant, either attaching at a nonstandard location or changing shape. In minimal rendering there are only two cases : RA live with Uvowelsign or UUvowelsign.
RAl + Uvs -> RUn
र + ु -> रु
R15
When the dependant vowel Ivs is used to override the inherent vowel of a syllable, it is always written to the extreme left of the orthographic syllable.
TAd + RAl + lvs -> T.RAn + lvs -> lvs + T.RAd
त् + र + ि -> त्र + ि -> त्रि
R16
The presence of an explicit virama blocks this reordering, and the dependant vowel is rendered after the rightmost such explicit virama.
TAd + ZWNJ + RAl + lvs -> TAd + lvs + RAl
त् + + र + ि -> त् रि
These sixteen rules for rendering of devanagari strengthen devanagari script . & also i would like to mention the currently progressing lohit devanagari on github [1] supports all of these rules & rendering principles as well .
1. https://github.com/pravins/lohit/tree/master/devanagari
- Background Information :
- About Devanagari :
- Standards :
2. Encoding Principles :
The writing systems constitute cross between syllabic & alphabetic writing systems. The effective unit of these writing systems is the orthographic syllable, consisting of consonant & vowel (CV) core & optionally with a canonical structure of (((C)C)C)V.
3. Rendering Devanagari :
>>Rules For Rendering :
R1
When nominal consonant preceeds a VIRAMA, it is considered to be a dead consonant . A consonant that does not precede VIRAMA is considered to be a live consonant .
TAn + VIRAMAn -> TAd
त + ् -> त्
R2
If ra+virama precedes a consonant , then it is replaced by superscript nonspacing mark "repha".
RAd + KAl -> KAl + RAsup
र् + क -> क + र् -> र्क
R3
If the "repha" is to be applied to a dead consonant & that dead consonant is combined with another consonant to form a conjunct , then the mark will be applied to the conjunct ligature form as a whole .
RAd + JAd+ NYAn -> J.NYAn +RAsup
र् + ज् + ञ -> ज्ञ +र् -> र्ज्ञ
R4
If the "repha" is to be applied to a dead consonant that is subsequently replaced by its half-consonant form, then the mark will get applied to the base of consonant cluster.
RAd + GAd + GHAl -> GAh + GHAl + RAsup
र् + ग् + घ -> ग् + घ + र् -> र्ग्घ
R5
In conformance with ISCII std , the half-consonat form is represented as eyelash-RA . This form of RA is commonly used in writing Marathi .
RRAn + VIRAMAn + YAn -> RRAh
ऱ + ् + य -> ऱ्य
RAd + ZWJ + YAn-> RAh
र् + + य -> ऱ्य
R6
Except for dead consonant RA, when a dead consonant precedes the live consonant RA,then dead consonant is replaced with its nominal form, and RA is replaced by subscript RAsub, which applies to nominal form.
TTHAd + RAl -> TTHAn + RAsub
ठ् + र -> ठ + ्र -> ठ्र
R7
For certain consonants, the mark RAsub may graphically combine with the consonant to form a conjuncts.
PHAd + RAl -> PHAn + RAsub
फ् + र -> फ + ्र -> फ्र
R8
If a dead consonant (other than RAd) precedes RAd, then the substitution of RA for RAsub is performed ; however, the VIRAMA that formed RAd remains to form a dead consonant conjuct form.
TAd + RAd -> TAn + RAsub + VIRAMAn -> T.RAd
त् + र -> त + ्र + ् -> त्र ्
R9
The nukta sign, which modifies a consonant form, is attached to that consonant in rendering. If the consonant represents a dead consonant, then NUKTA should precede VIRAMA .
KAn + NUKTAn + VIRAMAn -> QAd
क + ़ + ् -> क़्
R10
Other Modifying marks , in particular bindus , apply to the orthographic syllable as a whole. The bindus should follow any vowel signs. The relative placement of these marks is horizontal rather than vertical; the horizontal rendering order may vary according to typographic concerns.
KAn + AAvs + CANDRABINDUn
क + ा + ँ -> काँ
R11
If a dead consonant immediately precedes another dead consonant or a live consonant, then the first dead consonant may join the subsequent element to form a two-part conjunct.
JAd + NYAl -> J.NYAn
ज् + ञ -> ज्ञ
TTAd + TTHAl -> TT.TTHAn
ट् + ठ -> ट्ठ
R12
A conjunct ligature form can itself behave as a dead consonant & enter into further, more complex ligatures. A conjunct ligature form can also produce a half-form.
SAd + TAd + RAn -> SAd + T.RAn -> S.T.RAn
स् + त् + र -> स् + त्र -> स्त्र
R13
If a nominal consonant or conjunct ligature form precedes RAsub as a result of the application of rule R6, then the consonant or ligature form may join with RAsub to form a multi-part conjunct ligature.
KAn + RAsub -> K.RAn
क + ्र -> क्र
R14
In some cases, other combining marks will combine with a base consonant, either attaching at a nonstandard location or changing shape. In minimal rendering there are only two cases : RA live with Uvowelsign or UUvowelsign.
RAl + Uvs -> RUn
र + ु -> रु
R15
When the dependant vowel Ivs is used to override the inherent vowel of a syllable, it is always written to the extreme left of the orthographic syllable.
TAd + RAl + lvs -> T.RAn + lvs -> lvs + T.RAd
त् + र + ि -> त्र + ि -> त्रि
R16
The presence of an explicit virama blocks this reordering, and the dependant vowel is rendered after the rightmost such explicit virama.
TAd + ZWNJ + RAl + lvs -> TAd + lvs + RAl
त् + + र + ि -> त् रि
These sixteen rules for rendering of devanagari strengthen devanagari script . & also i would like to mention the currently progressing lohit devanagari on github [1] supports all of these rules & rendering principles as well .
1. https://github.com/pravins/lohit/tree/master/devanagari
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