<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><h2><div style="display: block;"><span style="font-size: 12px; font-weight: normal;">The latest version of the VOUnits/20231215/REC-VOUnits-1.1 document </span></div><div style="display: block;"><span style="font-size: 12px; font-weight: normal;">states that:</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: normal;">1.- In §2.2: empty strings are invalid</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: normal;">2.- In §2.2: the string </span><span style="font-size: 12px; font-weight: 400;">‘</span><span style="font-size: 12px; font-weight: normal;">1</span><span style="font-size: 12px; font-weight: 400;">’</span><span style="font-size: 12px; font-weight: normal;"> </span><span style="font-size: 12px; font-weight: 400;">indicated a dimensionless quantity</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">3.- In §2.8: data providers should use an empty string for unitless quantities</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">(excerpts from the standard are shown below)</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;"><br></span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">3. clearly contradicts 1. and 2. May I kindly ask for an errata? </span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;"><br></span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">Given the above, what shall I use for the units of the following unitless/dimensionless quantities:</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">- spectral resolving power (lambda/delta_lambda)</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">- SNR</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">- NCOMBINE (number of exposures co-added in a stacked image)</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">?</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;"><br></span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">Many thanks,</span></div><div style="display: block;"><span style="font-size: 12px; font-weight: 400;">Alberto</span></div></h2><h2><a id="tth_sEc2">2 The VOUnits syntax (normative)</a></h2></div><div><h3><a id="tth_sEc2.2">2.2 Parsing unit strings - overview</a></h3><font face="-webkit-standard" size="3">[…]</font></div><div><font face="-webkit-standard" size="3">The VOUnits syntax, though it also deems the empty string to be invalid, recognises the string </font><tt><span class="small"><span style="color: rgb(127, 76, 0);">1</span></span></tt><span style="font-family: -webkit-standard; font-size: medium;"> as positively indicating a dimensionless quantity.</span><div><span style="font-family: -webkit-standard; font-size: medium;"><br></span></div></div><div><span style="font-family: -webkit-standard; font-size: medium;"><br></span></div><div><h3><a id="tth_sEc2.8">2.8 Other symbols, and other remarks</a></h3></div><div><br></div><div><a><font color="#000000" face="-webkit-standard" size="3"><span style="caret-color: rgb(0, 0, 0);">[…]</span></font></a></div><div><a><font color="#000000" face="-webkit-standard" size="3"><span style="caret-color: rgb(0, 0, 0);">If there is no unit associated with a quantity (for example a quantity that is a character string, or unitless), data providers </span></font><b style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"><span style="color: rgb(0, 81, 156);">should</span></b><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: -webkit-standard; font-size: medium;"> indicate this with an empty string rather than blanks or dashes.</span></a></div></body></html>