Once you have mastered code replacements, you can combine multiple code replacements with variables to save time. In this example, you have a team of 4 photographers covering a music festival with 4 stages over a few days, and you want to download all their photos from different days into a single contact sheet. 

You could caption all those by hand, but setting up a code replacement file using multiple variables can speed things up exponentially. You could differentiate the images from each photographer by using the serial number of their camera since this is a unique variable that is already stored with each photo. 

This example code replacement file lists the serial number of each camera along with the name of each photographer, which stage they are covering, and the name of the performing artist, all separated with tabs, along with a simple single code replacement for the name of the music festival. 

51115555111555       Jimmy Bits         Montana Stage        Davide Crowie
13000000000031       Jane Lensy         Utah Stage           Motley Brew
12341234123412       Rita Reflex        Colorado Stage       Taylor Sleaux
78978978978978       Phil Filter        Texas Sage           Red Hot Eggplants
bmf                  Big Music Festival presented by Trustworthy Motors

(The actual code replacement file should use tabs between fields and not spaces.)

Even though there are photos from different photographers shooting different subjects in different locations on different dates, you can use the Metadata (IPTC) Template to batch apply a single caption in the IPTC Caption field for all photos from that shoot:

={serialnum}#3= performs on the  ={serialnum}#2= at the =bmf= on {monthname3} {day}, {year4}. Photo by staff photographer ={serialnum}#1=

For Jimmy, the replacements would make the captions read:

David Crowie performs on the Montana Stage at the Big Music Festival presented by Trustworthy Motors on Jan 6, 2013. Photo by staff photographer Jimmy Bits

While Rita's would read like this:

Taylor Sleaux performs on the Colorado Stage at the Big Music Festival presented by Trustworthy Motors on Jan 4, 2013. Photo by staff photographer Rita Reflex
That also means that if you have any last-minute changes in sponsorship, you can simply change the text in the code replacement file.