I am looking for a way to make the transaction and condition field required.... Can this be done in Epsilon?
Not sure if it was possible to do it in other themes but i was thinking about it to make it required.

Thanks

@mwindey
As in Epsilon those are select boxes, it should not be complicated.
For jQuery Validation, you have already way to do it in item-post.php (i.e. search for catId)

catId: {
  required: true,
  digits: true
}

catId: "Choose one category.",

You only need required part.

@MB Themes,

Piece off cake after your clear explanation  Thanks again! 

sTransaction: {
required: true,
digits: true
},

sTransaction: '<?php echo osc_esc_js(__('Transaction: this field is required.', 'epsilon')); ?>',

@mwindey
This part is redundant:
digits: true

@MB Themes,

Super! thanks 

Also added: $prepare['i_transaction'] = eps_get_session('sTransaction') <> '' ? eps_get_session('sTransaction') : '';

Let's dust off this topic with the following question  In item-post I check whether the transaction field has been filled in. However, if the price field is disabled in the category, this field is also not visible, but it is checked by jQuery Validation and a warning message that the field has not been completed appears. Is there a way that when the price field is inactive the check on transaction field is also disabled?

@mwindey
You have option to disable "extra fields" in selected categories - in theme settings.

@MB Themes

I tried that but as you now i did some modifications on item-post earlier.
    // Code for form validation
    $("form[name=item]").validate({
      rules: {
       sTransaction: {
         required: true,
        },
And that is the reason why it is checking if the field is correctly answered. When i remove that line it is not mandatory anymore for none of the catgories.. Now i am trying with:

<?php 
$excludedCategories = eps_get_session('catId');
if (!empty($excludedCategories)) {
    while (osc_has_categories()) {
        $categoryId = osc_category_id(); 
        if (in_array($categoryId, $excludedCategories)) {
            continue;
        }
        if ($categoryId == 8) {
            continue;
        }
        ?>
        sTransaction: {
            required: true,
        },
    <?php } ?>
<?php } ?>
But it's not working 

Solved in the javascript... When the price field is activated all is shown as is.... When pricefield disabled only transaction and condition fields show and  not mandatory anymore .... me happy 
    if(cat_id > 0) {
        if(catPriceEnabled[cat_id] == 1) {
            $('.item-publish section.s4').show(0).removeClass('hidden');
            $('.item-publish .status-wrap').fadeIn(200).removeClass('hidden');
            $('.item-publish .transaction-wrap').fadeIn(200).removeClass('hidden');
            $('.item-publish .condition-wrap').fadeIn(200).removeClass('hidden');
            $('.item-publish .selection').fadeIn(200).removeClass('hidden');
            $('.item-publish .in label[for="price"]').show();
            $('.item-publish .in .req').show();

        } else {
            $('.item-publish section.s4').show(0).removeClass('hidden');
            $('#price').val('');
            $('.item-publish section.s4 .or').hide(0).addClass('hidden');
            $('.item-publish .in label[for="price"]').hide();
            $('.item-publish .in .req').hide();
            $('.item-publish .status-wrap').fadeIn(200).removeClass('hidden');
            $('.item-publish .transaction-wrap').fadeIn(200).removeClass('hidden');
            $('.item-publish .condition-wrap').fadeIn(200).removeClass('hidden');
            $('.item-publish .selection').fadeOut(200).removeClass('hidden');
            $("#sTransaction, #sCondition").rules("remove");
        }