## 5 Discussion  
### Domains, Attributes, and Variables  
After listing the 18 SA that, to the best of our knowledge, users share to represent themselves, we investigated the ones which can disclose the SI principles according to SI Theory [19; 4; 10; 26], already examined in our previous research, regarding the methodology of the categorization of the social domains. The notions of Face, Frame, Stage, Time, and Activity or Performance were introduced and explained in [21; 67]; in this paper, they are linked to the notions of social determination and disclosure to draw the interrelations among social domains, attributes, and variables in a way that can benefit our understanding when designing privacy-aware systems. SA are categorized based on the general domains of SI which function as umbrella terms. Face can be disclosed through a user's name or surname, nickname, profile picture, gender, age, address or place of residence, education, affiliation, or job. Additional attributes can be drawn from a user's personal website, friend network, national or religious identity, class or income, or groups of interests and hobbies. Disclosing a user's photograph, address, place of residence, contact information, affiliations, job, friend network, national identity, or groups of interests can prove descriptive of their place of presence too. Moreover, time can be disclosed via SA on SM through photographs, education, affiliations, jobs, users' websites, and groups of interests. Furthermore, the Stage represents the combination of Frame and Time, so it sums up the total of the aforementioned attributes. Nicknames, photographs, education, affiliations, jobs, users' personal websites, friend networks, national or religious identities, class, income, political orientation, or groups of interest and hobbies can reveal information about a user's Activity or Performance. Table 2 combines the 5 general domains of SI and the 18 SA. Face discloses information on who users are, Frame is descriptive of Place, and Time refers to the attribute of when an action took place. Stage conveys information on both Place and Time, while Activity or Performance deals with information about what kind of actions the user performed. After the initial categorization, each of the SA on SM were examined, while possible explanations for disclosing attributes were discussed. Face can be disclosed through almost all SA. The most common practice for a user is to share his or her real name. Additionally, users may opt for a nickname as a SM username representation. In that case, even the fonts and pseudonyms of the users can represent parts of their identity to visualize representations of themselves while distinguishing themselves from others [13; 34; 39; 46; 68; 69; 70]. Nicknames can potentially reveal a user's Activity or Performance (MusicLover). Discussing online naming devices, we should mention the long discussion of researchers between using real names or pseudonyms online. Users are keen on using their real names, as some of the world's leading networking sites are pointing towards this direction, such as Facebook, Google, and LinkedIn [15]. Although this trend was not common during the early days of the internet, it has become extremely popular. Sharing photographs is another common practice among SM users, who upload enormous amounts of information [18]. Sharing pictures and videos is estimated to increase continuously as technology and SM grow [3]. In particular, users tend to share a desirable image of themselves [71], so they upload photos with positive (idealized) depictions, without any negative images [18; 48]. In extreme cases, such as the \"catfish\", users represent themselves in totally false identities for several reasons [18]. Alternatively, some users may opt for neutral depictions, such as pictures of flowers, landscapes, or cartoons, when choosing their profile picture [46]. Another famous practice is to share videos, which are much more descriptive than sharing photographs (a combination of image, motion, and sound) [45; 72; 40].