!!! Overview
[{$pagename}] is a [TLS ContentType] that describes a Step within the [TLS Handshake] process.

%%information
[{$pagename}] is removed in [TLS 1.3]
%%

Then the client sends a [{$pagename}] message, which is not a [TLS Handshake Message]: it has its own [TLS ContentType], so it will be sent in a [Record Protocol] of its own.
[{$pagename}] contents are purely symbolic (a single byte of value 1). This message marks the point at which the [client] switches to the newly negotiated [Cipher Suite] and [Master Secret] Key. All subsequent records from the [client] will then be sent using [Encryption].

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]