\textlf{} for light font weight – how common?

An example for HelveticaNeue-Light

\documentclass{article}
\usepackage{fontspec}
\setmainfont[
   ItalicFont     = HelveticaNeue-Italic,
   BoldFont       = HelveticaNeue-Bold,
   BoldItalicFont = HelveticaNeue-BoldItalic]{HelveticaNeue}
\newfontfamily\NHLight[
   ItalicFont     = HelveticaNeue-LightItalic,
   BoldFont       = HelveticaNeue-UltraLight,
   BoldItalicFont = HelveticaNeue-UltraLightItalic]{HelveticaNeue-Light}

\newcommand\textrmlf[1]{{\NHLight#1}}
\newcommand\textitlf[1]{{\NHLight\itshape#1}}
\let\textbflf\textrm
\newcommand\textulf[1]{{\NHLight\bfseries#1}}
\newcommand\textuitlf[1]{{\NHLight\bfseries\itshape#1}}

\begin{document}

\textrm{foo} \textbf{bar} \textit{baz} \textbf{\textit{foobar}} \par
\textrmlf{foo} \textbflf{bar} \textulf{bar} \textitlf{baz} \textuitlf{foobar}

\end{document}

in a texlive 2014, updated this morning I get the following from grep (with my annotation in comment at the end of each line):

$ grep "[^a-z]textlf[^a-z]" */*
allrunes/allrunes.sty:\DeclareTextFontCommand{\textlf}{\lfseries}
baskervaldx/Baskervaldx.sty:\DeclareRobustCommand{\textlf}[1]{%    lining figures
fbb/fbb.sty:\DeclareRobustCommand{\textlf}[1]{%    lining figures
heuristica/heuristica.sty:\DeclareRobustCommand{\textlf}[1]{%    lining figures
typeface/typeface.sty:      \PassOptionsToPackage{textlf}{MinionPro}%    lining figures
xcharter/XCharter.sty:\def\textlf#1{{\lfstyle #1}}%    lining figures


$ pwd
/usr/local/texlive/2014/texmf-dist/tex/latex

So it seems that the convention is that \textlf where used in all other packages denotes lining figures.