What is the if conditional code for : if profile field id is x

[basketmen]

Hi guys, i want to make one of text field in profile field, to cant be edited, only can viewed and saved default value, by add this code in userfield_textarea template : readonly="readonly"

its should be like this in red, wraped by the if conditional

<input type="hidden" name="userfield[{$profilefieldname}_set]" value="1" <if condition="$profilefield[field] == x">readonly="readonly" </if>/>

i already tried few if conditional codes like below, but looks like still wrong, what is the right if conditional code for this guys? thank you before

<if condition="$profilefield[field] == x">

<if condition="$profilefield[profilefieldid] == x">

<if condition="$field['fieldid'] == x">

<if condition="$fieldid == x">

[Lynne]

Perhaps:

<if condition="$profilefield[profilefieldid]">