Engineering notation requires a slightly modified scientific format in which the exponent is always divisible by 3.

The previous proposal was: In Part 1, 16.27.5 <number:scientific-number> change:
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The <number:scientific-number> element has the following attributes: number:decimal-places 19.343.4, number:grouping 19.348, number:min-exponent-digits 19.351 and number:min-integer-digits 19.352.
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to:
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The <number:scientific-number> element has the following attributes: number:decimal-places 19.343.4, number:exponent-base 19.xxx, number:grouping 19.348, number:min-exponent-digits 19.351 and number:min-integer-digits 19.352.
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In Part 1 insert section:
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19.xxx number:exponent-base
The number:exponent-base attribute determines the valid exponents to be used: the valid exponents are the integer multiples of the value of the number:exponent-base attribute. The defined values for this attribute are 1 and 3. The default value for this attribute is 1.
The number:exponent-base attribute is usable with the following element:
<number:scientific-number> 16.27.5.
The values of the number:exponent-base attribute are 1 and 3.
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In the schema change
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<define name="number-scientific-number-attlist">
<optional>
<attribute name="number:min-exponent-digits">
<ref name="integer"/>
</attribute>
</optional>
</define>
-----------------------------------------------------------------------
to
-----------------------------------------------------------------
<define name="number-scientific-number-attlist">
<interleave>
<optional>
<attribute name="number:min-exponent-digits">
<ref name="integer"/>
</attribute>
</optional>
<optional>
<attribute name="number:exponent-base">
<value>1</value>
<value>3</value>
</attribute>
</optional>
</interleave>
</define>
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In Part 1, 16.27.5 <number:scientific-number> change:
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The <number:scientific-number> element has the following attributes: number:decimal-places 19.343.4, number:grouping 19.348, number:min-exponent-digits 19.351 and number:min-integer-digits 19.352.
-----------------------------------------------------------------
to:
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The <number:scientific-number> element has the following attributes: number:decimal-places 19.343.4, number:exponent-interval 19.xxx, number:grouping 19.348, number:min-exponent-digits 19.351 and number:min-integer-digits 19.352.
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In Part 1 insert section:
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19.xxx number:exponent-interval
The number:exponent-interval attribute determines the valid exponents to be used: the valid exponents are the integer multiples of the value of the number:exponent-interval attribute. The default value for this attribute is 1.
The number:exponent-interval attribute is usable with the following element:
<number:scientific-number> 16.27.5.
The number:exponent-interval attribute has the data type positiveInteger 18.2.

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In the schema change
-----------------------------------------------------------------
<define name="number-scientific-number-attlist">
<optional>
<attribute name="number:min-exponent-digits">
<ref name="integer"/>
</attribute>
</optional>
</define>
-----------------------------------------------------------------------
to
-----------------------------------------------------------------
<define name="number-scientific-number-attlist">
<interleave>
<optional>
<attribute name="number:min-exponent-digits">
<ref name="integer"/>
</attribute>
</optional>
<optional>
<attribute name="number:exponent-interval">
<ref name="positiveInteger"/>
</attribute>
</optional>
</interleave>
</define>
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