According to the instructions in the comments:
"If you want to insert the identifiers you can do so either as a comma separated list of links, just like they are displayed in the Book details panel,..."
How is that formatted, I do not see the coding details. I only see the following:
{display.identifiers}
{identifiers.links}
{identifiers.display.isbn}
display.identifiers returns the text "Initial" if any identifier and "none" otherwise. And the links only will display the isbn as a link. But nothing about how to return all identifiers... as stated?
Side comment, "identifiers.display.isbn" ... seems like using "display" here is confusing, as "display" used in other cases for use with the display CSS tag. If I were to specify I would expect something like
{display.identifiers} - as is
{identifiers.isbn.link} - display the 1 isbn (if there is one) as a link
{identifiers.isbn} - display the 1 isbn (if there is one) as text
{identifiers} or perhaps {identifiers.text} display all identifiers just as it shows in the edit metadata GUI
{identifiers.select('text-string')} - display the 1 value (if it exists) for the identifier with the name "text-string"
If all cases, if there is none available, return empty string
[Note there can only be one isbn since that field is setup not allow more than one]
Example, the following is entered in the Ids GUI:
isbn:9781101188057, isbn-p:9780399156434, asin:B002DW936A
{display.identifiers} will return "Initial"
{identifiers.isbn.link} will return "<a href="https://www.worldcat.org/isbn/9781416587101" title="isbn:9781101188057">9781101188057</a>"
{identifiers.isbn} will return "9781101188057"
{identifiers.text} will return "isbn:9781101188057, isbn-p:9780399156434, asin:B002DW936A"
{identifiers.select('isbn-p')} will return "9780399156434"