Nomenclature of carbohydrates
It's really strange and contradictory info, I don't know what the ii paragraph is talking about. Referencing the source as “my book” makes is hard to verify and e.g. check if there is some illustratory graphics.

To the last paragraph: The cited information would lead to e.g. “D(+)-glucose”, which is not consistent with typographical details of IUPAC nomenclature of carbohydrates (or IUPAC nomenclature of organic chemistry). The correct name would be (+)-ᴅ-glucose.[1]


  2-Carb-4.5.&nbsp; Optical rotation
  
  If the sign of the optical rotation under specified conditions is to be indicated, this is done by adding (+)- or (−)- before the configurational prefix. Racemic forms are indicated by (±)-.
  
  Examples:
  
  ᴅ-Glucose or (+)-ᴅ-glucose
  ᴅ-Fructose or (−)-ᴅ-fructose
  ᴅʟ-Glucose or (±)-glucose


Fructose is an example of laevorotatory ᴅ- sugar (therefore is also called levulose).

The stereochemical configuration (especially when it is of one of many chiral atoms, and in sugars, sometimes it's the one that forms the acetal group of the major cyclic form, in some sugars not) is not directly related to the physical optical rotation.

References:


Nomenclature of Carbohydrates (Recommendations 1996), 4.5. Optical rotation