Hi Sergey,
The way a tiddler is displayed is determined by $:/core/ui/ViewTemplate . It loads the template in pieces, each of them has the tag
$:/tags/ViewTemplate (you can see the list using the filter [tag[$:/tags/ViewTemplate]].
The subtitle template, $:/core/ui/ViewTemplate/subtitle, is just one of them.
If you don't like the information that is currently in the subtitle, you can over-write the tiddler with an empty tiddler of the same name, or you can remove its tag.
If you want additional information to be displayed instead, you can edit the subtitle tiddler with different wikitext, or you can add a new tiddler that also has the tag $:/tags/ViewTemplate, which will then also become part of the view template.
For example, if you make a tiddler called "Sergey's View Template component" and give it the tag $:/tags/ViewTemplate and the content
<a href={{!!url}} target="blank">{{!!info}}</a>
then every tiddler that has the necessary fields will display some "info" that links to a "url".
To make this piece of the view template appear where we want it to, we can give it the fields "list-before" or "list-after", for example, you can give this tiddler the field list-after, with a value of $:/core/ui/ViewTemplate/subtitle and it will appear below the subtitle.
If you want to combine these two approaches, you could re-write the subtitle template to look like this:
<$reveal type="nomatch" state=<<folded-state>> text="hide" tag="div" retain="yes" animate="yes">
<div class="tc-subtitle">
<$list filter="[is[current]!has[info]]">
<$link to={{!!modifier}}>
<$view field="modifier"/>
</$link> <$view field="modified" format="date" template={{$:/language/Tiddler/DateFormat}}/>
</$list>
<$list filter="[is[current]has[info]]">
<a href={{!!url}} target="blank">{{!!info}}</a>
</$list>
</div>
</$reveal>
And it will display the link for tiddlers that have an "info" field and revert to default behaviour for those that don't.
If anything is unclear, please ask.
Regards,
Richard