Meaning of 'Version'?

[Joop Jagers]

In the tab "Ranges" in Format t-Settings there are 4 versions selectable under "Contents and Layout". What's the difference between these Versions?

[Dave Crosby]

Erwin has put SO MUCH stuff in this product!
Even though I have been using it for 4 years, I had never noticed this item.



I looked it up in the manual and found:

The Ranges page on the Font Settings window has several fields related to character ranges and additional metrics. On the Format menu, click Settings, and then click the Ranges tab.

Version

After version 0 some additional fields where (were?) included and updated:

Version 1 includes the Code Page Character Range.

Version 2 updated Unicode Character Ranges and includes the Additional Metrics fields.

Version 3 updated Unicode Character Ranges



Average Character Width

This field currently has two different descriptions that depend on the Version field.



For version 0, 1 and 2:

The Average Character Width parameter specifies the arithmetic average of the escapement (width) of all of the 26 lowercase letters a through z of the Latin alphabet and the space character. If any of the 26 lowercase letters are not present, this parameter should equal the weighted average of all glyphs in the font. For Symbol fonts use the unweighted average.



Comments: This parameter is a descriptive attribute of the font that specifies the spacing of characters for comparing one font to another for selection or substitution. For proportionally spaced fonts, this value is useful in estimating the length for lines of text. The weighting factors provided with this example are only valid for Latin lowercase letters. If other character sets, or capital letters are used, different frequency of use values should be used. One needs to be careful when comparing fonts that use different frequency of use values for font mapping. The average character width is calculated according to this formula: For the lowercase letters only, sum the individual character widths multiplied by the following weighting factors and then divide by 1000. For example:



Letter Weight Factor

a 64

b 14

c 27

d 35

e 100

f 20

g 14

h 42

i 63

j 3

k 6

l 35

m 20

n 56

o 56

p 17

q 4

r 49

s 56

t 71

u 31

v 10

w 18

x 3

y 18

z 2

space 166



For version 3:

The Average Character Width parameter specifies the arithmetic average of the escapement (width) of all non-zero width glyphs in the font.



Use the Calculate button to calculate the Average weighted escapement based on the current metrics.

Note: it is not necessary to modify this field when Recalc average char width is selected on the Font tab in the Options window (available through the Tools menu).



Unicode Character Ranges

This field is used to specify the Unicode blocks or ranges encompassed by the font file in the mappings for the Microsoft platform. The Ranges depend on the selected Content and Layout version. Press the Edit button to modify this field through the Unicode Character Range window or press the Calculate button the generate the value.



Code Page Character Ranges

This field is used to specify the code pages encompassed by the font file in the mappings for the Microsoft platform. Press the Edit button to modify this field through the Code Page Character Range window or press the Calculate button the generate the value.



Additional Metrics

x-Height

This metric specifies the distance between the baseline and the approximate height of non-ascending lowercase letters measured in Funits. This value would normally be specified by a type designer but in situations where that is not possible, for example when a legacy font is being converted, the value may be set equal to the top of the unscaled and unhinted glyph bounding box of the glyph encoded at U+0078 (LATIN SMALL LETTER X). If no glyph is encoded in this position the field should be set to 0.



This metric, if specified, can be used in font substitution: the xHeight value of one font can be scaled to approximate the apparent size of another.



CapHeight

This metric specifies the distance between the baseline and the approximate height of uppercase letters measured in Funits. This value would normally be specified by a type designer but in situations where that is not possible, for example when a legacy font is being converted, the value may be set equal to the top of the unscaled and unhinted glyph bounding box of the glyph encoded at U+0048 (LATIN CAPITAL LETTER H). If no glyph is encoded in this position the field should be set to 0.



This metric, if specified, can be used in systems that specify type size by capital height measured in millimeters. It can also be used as an alignment metric; the top of a drop capital, for instance, can be aligned to the CapHeight metric of the first line of text.



MaxContext

The maximum length of a target glyph context for any feature in this font. For example, a font which has only a pair kerning feature should set this field to 2. If the font also has a ligature feature in which the glyph sequence 'f f i' is substituted by the ligature 'ffi', then this field should be set to 3. This field could be useful to sophisticated line-breaking engines in determining how far they should look ahead to test whether something could change that effects the line breaking. For chaining contextual lookups, the length of the string (covered glyph) + (input sequence) + (lookahead sequence) should be considered.



DefaultChar

Whenever a request is made for a character that is not in the font, Windows provides this default character. If the value of this field is zero, glyph ID 0 is to be used for the default character otherwise this is the Unicode encoding of the glyph that Windows uses as the default character.



BreakChar

This is the Unicode encoding of the glyph that Windows uses as the break character. The break character is used to separate words and justify text. Most fonts specify that 'space' is the break character.

[Joop Jagers]

Thank you SO much! What a polite way to say 'read the (...) manual'!