When creating or editing a Custom Field with any merge tag, we now have the option to leave a tag as a blank line when not otherwise populated.
The blank line option works so that if the field is left blank in the case, the tag will populate as a line instead. It is what might be used for a signature line.
"If this box is checked and if the field is left blank in a case, this tag will be replaced with a blank line to be filled out later."
You can make the line smaller by deleting part of the line, or you can increase the length by adding underscores.
Blank Line Option:
When creating or editing your document in My Account Settings > Doc Creator Templates, you can place the tag which includes the Blank Line Option in your form or document template.
Per your custom fields tag instructions, a blank line will appear where your tag was placed if it has not been otherwise completed:
***Keywords: Custom Fields, Blank Line, Leave Blank, Blank Field.