Crisis of Notation, italic or roman subscripts?

[Ashiataka]

From the wikipedia article Physical Quantity

Name reference: The quantity has a subscripted or superscripted single letter, a number of letters, or an entire word, to specify what concept or entity they refer to, and tend to be written in upright roman typeface rather than italic while the quantity is in italic. For instanceEk or Ekinetic is usually used to denote kinetic energy and Ep or Epotential is usually used to denote potential energy.
Quantity reference: The quantity has a subscripted or superscripted single letter, a number of letters, or an entire word, to specify what measurement/s they refer to, and tend to be written in italic rather than upright roman typeface while the quantity is also in italic. For example cp or cisobaric is heat capacity at constant pressure.
Note the difference in the style of the subscripts: k and p are abbreviations of the words kinetic and potential, whereas p (italic) is the symbol for the physical quantity pressure rather than an abbreviation of the word "pressure".

I'm having trouble deciphering the difference here between when roman or italic is appropriate.

Any further guidance?

Thank you.

 

[Enigman]

My understanding is -
The quantity is always in italics.
Name reference - subscript refers to the concept or entity (usually with an abbr.); written upright.
Quantity reference - subscript refers to under what condition measurement was taken (with a symbol for the quantity taken as constant); written in italics.

Basically, accepted symbols are in italics; abbreviations are not.

 

[zoobyshoe]

Notice, Ashiataka, that the choice is between upright or italic, not Roman or italic. Roman seems to be the conventional font, and it may either remain upright or be italicized.

 

[DrClaude]

Notice, Ashiataka, that the choice is between upright or italic, not Roman or italic. Roman seems to be the conventional font, and it may either remain upright or be italicized.

From Wikipedia:

In Latin-script typography, roman is one of the three main kinds of historical type, alongside blackletter and italic.

 

[DrClaude]

I concur with Enigman. Note that Physical Review has a different rule: all single-letter subscripts must be italic, even if they don't refer to a quantity. For example, the initial time could be noted $t_\mathrm{i}$, except in Physical Review where it must be $t_i$.

 

[zoobyshoe]

From Wikipedia:

I stand corrected. I thought Roman was a font that could be left upright, italicized, bolded, or underlined like any font.

 

[BobG]

I stand corrected. I thought Roman was a font that could be left upright, italicized, bolded, or underlined like any font.

Yes, Roman, like any text, can be italicized on a computer. That's not the same as an Italic font, which can similarly be modified into an upright Italic font (one of the options when you need to italicize something in the middle of a text that's already italicized).

With computers and tons of fonts, you can italicize anything with that meaning "slanted letters" for a lot of the fonts.

In the old days of typesetting, italics was its own font and still is, even if not as significant anymore in normal text. Who the heck wants to actually change fonts all the time when using slanted letters is simpler and almost as effective.

Back in the days I used a typewriter, I just plain hated italicized text in a paper. I had to insert two blocks of wood, just the write size, under the two right feet of the typewriter in order to get just the right slant for the italicized letters.

 

[zoobyshoe]

Yes, Roman, like any text, can be italicized on a computer. That's not the same as an Italic font, which can similarly be modified into an upright Italic font (one of the options when you need to italicize something in the middle of a text that's already italicized).

With computers and tons of fonts, you can italicize anything with that meaning "slanted letters" for a lot of the fonts.

In the old days of typesetting, italics was its own font and still is, even if not as significant anymore in normal text. Who the heck wants to actually change fonts all the time when using slanted letters is simpler and almost as effective.

I guess my sense of it came completely from internet usage, and I never ran across the history.

Back in the days I used a typewriter, I just plain hated italicized text in a paper. I had to insert two blocks of wood, just the write size, under the two right feet of the typewriter in order to get just the right slant for the italicized letters.

Oh, the right side! I never had any luck with this because I was always blocking up the left side! My reasoning was that friction should prevent the bottom of the letters from moving while the tops fell to the right.