What is "params" as an AT command?

Hi everyone! Thank you for your help!
I don't understand the function of "params" here

 mySerial.println("params=" + data1 + "~" + data2);

It is sent to a SIM800L module as an AT command; but I can't find "params" in AT command manual; so probably it's something else.

Any help?

Here is the full sketch.

#include <SoftwareSerial.h>
#include <Wire.h>

SoftwareSerial mySerial(7, 8);            // RX, TX Pins
String apn = "apn.fastweb.it";                       //APN
String apn_u = "";                     //APN-Username
String apn_p = "";                     //APN-Password
String url = "http://www.google.com";  //URL for HTTP-POST-REQUEST
String data1;   //String for the first Paramter (e.g. Sensor1)
String data2;   //String for the second Paramter (e.g. Sensor2)



void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
  delay(5000);

    data1 = "123";
    data2 = "ABC";
    gsm_sendhttp(); //Start the GSM-Modul and start the transmisson
    delay(60000); //Wait one minute

}


void loop() { // run over and over


}


void gsm_sendhttp() {
  
  
 
  Serial.println(">>AT");
  mySerial.println("AT");
  runsl();//Print GSM Status an the Serial Output;
  Serial.println("");
  delay(4000);
  Serial.println(">>AT+SAPBR=3,1,Contype,GPRS");
  mySerial.println("AT+SAPBR=3,1,Contype,GPRS");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+SAPBR=3,1,APN," + apn);
  mySerial.println("AT+SAPBR=3,1,APN," + apn);
  runsl();
  Serial.println("");
  delay(100);
  //mySerial.println("AT+SAPBR=3,1,USER," + apn_u); //Comment out, if you need username
  //runsl();
  //delay(100);
  //mySerial.println("AT+SAPBR=3,1,PWD," + apn_p); //Comment out, if you need password
  //runsl();
  delay(100);
  Serial.println(">>AT+SAPBR =1,1");
  mySerial.println("AT+SAPBR =1,1");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+SAPBR=2,1");
  mySerial.println("AT+SAPBR=2,1");
  runsl();
  Serial.println("");
  delay(2000);
  Serial.println(">>AT+HTTPINIT");
  mySerial.println("AT+HTTPINIT");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+HTTPPARA=CID,1");
  mySerial.println("AT+HTTPPARA=CID,1");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+HTTPPARA=URL," + url);
  mySerial.println("AT+HTTPPARA=URL," + url);
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+HTTPPARA=CONTENT,application/x-www-form-urlencoded");
  mySerial.println("AT+HTTPPARA=CONTENT,application/x-www-form-urlencoded");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+HTTPDATA=192,10000");
  mySerial.println("AT+HTTPDATA=192,10000");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>params=" + data1 + "~" + data2);
  mySerial.println("params=" + data1 + "~" + data2);
  runsl();
  Serial.println("");
  delay(10000);
  Serial.println(">>AT+HTTPACTION=1");
  mySerial.println("AT+HTTPACTION=1");
  runsl();
  Serial.println("");
  delay(5000);
  Serial.println(">>AT+HTTPREAD");
  mySerial.println("AT+HTTPREAD");
  runsl();
  Serial.println("");
  delay(100);
  Serial.println(">>AT+HTTPTERM");
  mySerial.println("AT+HTTPTERM");
  runsl(); 
  Serial.println("");
  Serial.println(">>AT");
  mySerial.println("AT");
  runsl();//Print GSM Status an the Serial Output;
  Serial.println("");
  Serial.println(">>AT");
  mySerial.println("AT");
  runsl();//Print GSM Status an the Serial Output;
  Serial.println("");
}

//Print GSM Status
void runsl() {
  delay(500);
  while (mySerial.available()) {
    Serial.write(mySerial.read());
  }

}

It is part of the HTTP request you are sending to the URL. It is not part of the AT command set

Ok, thank you!
Salvatore