Alternate I exists in caps but not Small Caps

[frankrolf]

The capital I has a slab-serif alternate, I.a. The same kind of alternate does not exist in the Small Caps – which may or may not be a conscious decision.

[JimEBlevins]

Please make the slab-serif (serif?) capital I the default, so that even isolated it can be easily distinguished from lower-case ell and one (l and 1), in the spirit of the legibility-standard DIN 1450.

In Open Office, this is denoted Source Sans 3:ss01.

(Thank you for the superb font, especially its ell.)

Bigelow, Charles. ``Oh, oh, zero!''. TUGboat 34, no. 2 (2013): 168-181. https://www.tug.org/TUGboat/tb34-2/tb107bigelow-zero.pdf

[pauldhunt]

@StatisticalProgrammer Thanks for your input, however I feel that the current designs are suitably differentiated by the tail + ascender height on l (⬇️L) and the foot on 1. I feel no need to follow the DIN standard as this typeface is not trying to be DIN.

[JimEBlevins]

Thank you, @pauldhunt, for the informative reply.

The image was generated with these lines from the LaTeX source-code (fontspec):

Source Serif%

&\SourceRm{1\textsc{L\textcolor{blue}{1} Ileum rnai}}%

&\textbf{\SourceRm{1\textsc{L\textcolor{blue}{1} Ileum rnai}}}%

&NA%\textit{\SourceRm{\textsc{NA}}}%

&NA%\textbf{\textit{\SourceRm{\textsc{NA}}}}\\

Source Sans%

&\textsf{1{\textsc{L\textcolor{red}{1} Ileum rna\textcolor{red}{i}}}} 

&\textsf{\textbf{1{\textsc{L\textcolor{red}{1} Ileum rna\textcolor{red}{i}}}}}%

&NA%(\textit{{\textsc{\textsf{L1 Ileum rnai}}}})

&NA%(\textsf{\textit{\textbf{\textsc{L1 Ileum rnai}}}})\\

Thanks again for the great family of typefaces.

[JimEBlevins]

Source Sans has in its fractional numerals the 1 without the lower serif, according to this Youtube video from fontribute (TypeThursday's Thomas Jockin, with Erin McLaughlin):

Exploring fonts for User Interfaces: Fontribute of Source Sans and Fira Sans https://www.youtube.com/watch?v=pK0KPd481-M

As this is a design choice consistent with the fractions (rather than a semantic error), The above graphic should change the red 1 to a blue.

[miguelsousa]

@StatisticalProgrammer I've wrapped the LaTeX code above with backticks to make it a fenced code block with syntax highlighting.