## 4 Discussion
For example, the reference charts of sitting height (SH), subischial leg length (SLL), and the sitting height/leg length ratio (SH/LL) are useful tools in assessing body proportion for clinicians and researchers in related areas [44]. Many studies have demonstrated differences between national and WHO reference curves in children older than 5 years [45]. Unfortunately, reference curves for body proportions (SH, SLL, and their ratio) based on state-of-the-art statistics are not available. Research in China in the nineties of the 20 th century [46] found that the arm span to standing height ratio and the upper segment to lower segment ratio are the most useful parameters in describing body proportions. Similar results were confirmed on Japanese children, where the results highlight the usefulness of the Body Proportion Chart method for identifying changes in body proportions during adolescence [47]. It is evident that certain canons also change with age during a child's development towards adulthood. According to the obtained data, it was determined that the changes in the canon are related to all the corresponding harmonic changes of the body in the growth of every healthy child. Applying calculations based on the canons and the harmonic circle could be much simpler than demanding anthropometric measurements, which would speed up the collection of anthropometric data. The novelty of this research is in the idea of establishing a newer and simpler way of obtaining anthropometric data instead of complex anthropometric measurements and to establish a head-body canon in the future as a measure for creating a potential new anthropological-biomechanical model. Several important findings emerge from this research that confirm the set hypotheses:  
* The existing data established in research [5; 6; 21; 24] on the canon (ratio) of children's head length (HL) to total body height (BH) coincide with the results of our research, which range from 5.59 and 5.72 (2-year-old girls and boys) to 7.50 and 7.60 (15-year-old boys and girls), depending on age and gender. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Autor** & \begin{tabular}{c} **[20] [PERSON] (1914)** \\ **(1 st Century BCE)** \\ \end{tabular} & \
\begin{tabular}{c} **[24] [PERSON] (1889) [5] [PERSON]** \\ **(1989)** \\ \end{tabular} &
\begin{tabular}{c} **[6] [PERSON] (2001)** \\ \end{tabular} & **Results (2024)** \\ \hline \multicolumn{4}{c}{**Children’s Age**} & \multicolumn{3}{c}{**Canon (HL)**} \\ \hline
4–5 & No data & No data & 5.5 HL & 5.99 HL \\
5–6 & No data & 5.5 HL & No data & 6.18 HL \\
10–11 & No data & 6.0 HL & No data & 6.80 HL \\
14–15 & No data & 7.0 HL & No data & 7.63 HL \\
21–35 & 8 HL & 7.5 HL & 8 HL & No data \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of canons by different authors through the years. * Compared to existing data from the literature (Table 6), the canon has increased with regard to the observed age of children, which confirms the secular trends of the past 100 years. * Observing the growth and development of a child's body in relation to an adult, it is obvious that the corresponding canons change faster with age. * Although the canons for boys and the girls of the same age are similar, they must be observed separately. * Studies should consider not only the age and gender, but also the origin, nationality, and other sociodemographic parameters of the child in future research. We are aware of significant limitations in this research, which are mainly from an anthropometric-medical point of view. Primarily, we used twenty-year-old anthropometric data for school children, simple measuring instruments, and were not focused on anthropometric databases and secular trends. As well, the research was focused on the geographical locations of the Balkan countries where the white Slavic race predominates and where there is very little mixing with other ethnic groups.