Complex volume and issue values

Complex volume and issue values may be encoded using underscores to represent spaces.

Use 'Supplement' for volume or issue supplements and 'Part' for multi-part volumes or issues. This must be followed by an underscore and a numeric value.

Capture double issues with a hyphen between the issue numbers

Volume 1 Supplement 1

<volume>1</volume>
<issue>Supplement_1</issue>

Volume 1 Issue 1 Part 2

<volume>1</volume>
<issue>1_Part_2</issue>

Volume 1 Issue 1-2

<volume>1</volume>
<issue>1-2</issue>