In one Modal Dialog form (dlg_closeopp.aspx) there's code as such:
<%@ Register TagPrefix="loc" Namespace="Microsoft.Crm.Application.Controls.Localization" Assembly="Microsoft.Crm.Application.Components.Application" %>
<loc:Text ResourceId="Web.SFA.opps.dlg_closeopp.aspx_176" runat="server"/>
And when I run this in web browser I see this text at this place "Status". So this is localization resource but I have no idea where it comes from.
What is _176 a line number? Adress?
I want to make a localization as such for my custom Modal dialog.
(My question is in bold).
So this is localization resource but I have no idea where it comes from
Short Answer: Language Packs.
Long Answer: CRM can be localized by using Language Packs, for all the available language packs, out of the box attributes translations are shipped from Microsoft. If you have custom attributes on an entity you want to translate, you need to Export/Import translations.
Create a solution with the entity and the attributes you want to localize. Export the "Translations" out, unzip the file and edit "Crm Translations" using excel file, look for the "Display Strings/Localized Labels" tabs in the excel. Once you have updated your translations, re-zip the file and import into CRM.
What is _176 a line number? Adress?
They are just display string keys used by CRM internally to store key value pairs of translated text. You can find them in the "Display Strings" tab in the "Crm Translations" excel sheet. If you want to use a field's label as a localized string, you'd reference the "Display String Key" like in example you have provided.