Back to my favorite subject!
In Classic Traveller and the Cepheus Engine, Skill-0 means basic training and literacy in the subject which is sufficient to perform some tasks but insufficient for gaining employment in the field. Skill-1 is employable and in CE can earn you very good pay in some cases.
|My dear mother|
For example, My mother knows how to check her e-mail, do basic Google searches, take pictures with her phone camera, type at a reasonable speed, and use KODI (and similar streaming services). However, she would be clueless in any further technical task, even installing updates on her Linux Lite machine or installing apps on her phone from Google Play. That would be Unskilled in CE terms.
|The soon-to-be Mrs. Stellagama|
My fiancee knows how to operate a computer, an Android phone, or an Android streamer, including updating, installing new apps, and even installing and configuring KODI extensions. She knows that the solution to 50% of basic computer problems is a restart and can also solve several other basic issues, both ones related to loose connectors and some software issues. She knows the basics of MSOFFICE use but not any more advanced tricks. That would be Skill-0 in CE terms.
I have good knowledge of messing around with Windows and various Ubuntu distros, assembling a computer from parts I buy, advanced MSOFFICE functions, advanced Google search functions, and how to solve a wide range of software related issues (even a few hardware ones). I can write simple but very readable and well-organized scripts in Python. I type at 50 or so words per minute. I use many of these skills as part of my job which combines translation, editing, content editing, and information services. That would be Skill-1 in CE terms.
This is one reason I like the Classic Traveller skill system. Skill levels are not an incremental increase in your roll bonus, but rather denote actual very different levels of skill and are quite "realistic". This is the difference between unskilled (untrained), having basic literacy in the area (Skill-0), having a baseline employable skill (Skill-1), being a lower-level certified professional (Skill-2), having a full-blown Profession (Skill-3) or being an expert (Skill-4+).
In medicine: Medicine-0 is first-aid/CPR training; Medicine-1 is a paramedic; Medicine-2 is a registered nurse (a certified professional) or a medical intern; Medicine-3 is a proper doctor (a Profession); experts have Medicine-4 or higher.
This also explains the CT training rules - which I intend to port into CE. At this scale of skills, the gradual accumulation of experience alone can rarely bring you from one level to another. You need both experience and study. You can teach yourself in some cases, but this requires dedication.
How many nurses (Medicine-2 and let's say DEX 8) gain the medical knowledge and proficiency of a surgeon (Medicine-3 and DEX 8) simply by working as a nurse for a decade or two? This requires deliberate training, as well as practice. It also takes time, and not everyone succeeds in this.
How many trained combat soldiers (Gun Combat-1) become designated sharpshooters (Gun Combat-2) or snipers (Gun Combat-3) after a tour of duty or even several tours of duty, simply by being soldiers and using their gun a lot? Again, this needs deliberate training (or at least self-training) and practice. Not everyone will be able to do so.
How many people belong to two Professions (say, Skill-3 in both Medicine and Engineering) at the same time? Some do, but this is uncommon.
|Ellen Ripley. Badass with 5 skill points!|
Many people will never be 'proper' high-level Professionals. Many sci-fi heroes are not "Professionals". Ellen Ripley, from Alien(s), would be (in CT) UPP 67C997 Merchant 4th Officer, 3 terms, age 30, Vacc Suit-2, Pilot-1, Navigation-1, Admin-1. In CE, she will also have several Skill-0's. Only 5 skill points, highest skill at 2. Enough for boundless sci-fi heroism and adventure!
This is not D&D. You don't go "zero to hero" in Traveller or CE. You are a skilled adult, sometimes a professional. But there is a sharp limit on what you can learn and on how far further experience and training can get you.